No picnic
I was sent a warning about a virus called jdbgmgr. exe, which supposedly can wipe files. I found it on my hard drive (with a teddy bear icon) and deleted it. I use AVG6 anti-virus and it was not detected, and apparently the main anti-virus programs also miss it. Heard of it? K Docherty,
Twickenham

Jack Schofield replies: Almost everyone seems to have fallen for this one, in spite of the fact that it is only the old SULFNBK hoax under another name. However, putting "jdbgmgr.exe virus" into Google would have shown it was a hoax in seconds. You can replace the file by installing the current version of Microsoft's Virtual Machine, used to run Java applets, but it is probably not worth the effort. See Availability of Current Build of Microsoft VM (Q163637). As usual, restart your PC and do not run any other programs before getting the update.

Bigfoot
I have several accounts listed in Outlook Express, such as Bigfoot Internet Directory Service and InfoSpace Business Directory Service. How do these accounts come to be set up? Can I delete them safely? Alan Taylor

JS: These services are preinstalled to help you. If you go to Edit|Find|People, this defaults to searching your address book. But if you click the down-arrow for the Look In box, you will be given the option to search a number of directory services such as the ones you mention. You could delete them, but there is no real benefit. You could also try searching for your own name in the various directories.

Only delete
All the emails I have deleted are stored in a Deleted items.dbx folder in Windows/Application data/Identities. I have opened the file in Notepad and find it even contains dodgy emails that I "deleted" unopened and unread. Brian Campbell

JS: The Deleted items folder should be visible in the Folders section of Outlook Express. If not, select View Layout, tick Folder List and click OK. To empty the folder, right-click on it and select Empty "Deleted Items" Folder from the drop-down list. You could also go to Tools|Options| Maintenance and tick the box next to Empty messages from the "Deleted Items" Folder on exit, but I don't recommend it. Close down Outlook Express, select your C: drive in Windows Explorer, press F3 and search for *.dbx files. You may still have one or more large Deleted items.dbx files. You can delete these if you are sure you will never need to recover any of the contents. When you restart Outlook Express, it will automatically create a new file.

Slow SE
Windows Explorer (in Windows 98SE) becomes increasingly slow. After about 15 minutes of continuous use, all operations (deleting, renaming, etc), take minutes to complete. However, the same operations can be carried out in a Dos window at full speed. Altering the View settings or restarting the program makes no difference. A Smith

JS: The most likely causes are a virus, a memory leak in a background program that is consuming all your PC's resources, and a problem with the way Windows is set up. Start by running a virus check. Next, press Ctrl-Alt-Del and find out which programs are running in the background. Stop all of these from loading except Explorer and Systray and see if it solves the problem. If not, think about reinstalling Windows from scratch. Microsoft suggests the problem is caused by having too many files in directories: see Opening a Folder Takes a Long Time (Q153114).

Try limiting each directory to a maximum of 256 files. However, hundreds of millions of people have thousands of files in some directories (eg C:\Windows\System) and these work fine, so I find this unconvincing. The best web page I can find on the topic is at the-it-mercenary.com. You could try "the Sean option". Alternatively, you could replace Windows Explorer with Ontrack's PowerDesk 5, which is much better. There is a free version.

Backchat
· The problems with the Alcatel USB modem for ADSL and PCs with VIA chipsets, raised last week, affected several readers. Dr Bob Rollins complained about users having to carry the can for what looks like a defect either in the Alcatel modem, or PCs with USB ports and VIA chipsets, or in the USB specification. "It's galling to sign up to a service - as I did with BT Openworld - to find that you're locked into a one-year contract but that the service might not work with a PC that meets all the requirements advertised on the service provider's website."

David Latimer said: "What solved it was buying a Belkin 4 USB port card. I think I got it from Dabs for around £28." Warren Newman added: "there is a similar problem with Apple Macs connected to ADSL. The current Alcatel drivers turned out to be the cause of periodic 'kernel panics' (crashes) on my allegedly crash-proof OS X system. Alcatel is aware of the problem and will be rewriting the drivers for OS X." Robert Clayson pointed out that the Alcatel modem was not the only USB product to have problems with VIA boards: "I have a Psion Wavefinder, which I must also run through a separate hub because of the power it demands."

· Several readers, including Matt Purver, pointed out that Mozilla/Netscape 6 can stop popup adverts. Wasim Juned added: "If you're running Opera 6 you can refuse pop-up windows by clicking on File, then Preferences, and Refuse pop-up windows."

· More on leaving laptops switched on all the time. Peter May says that IBM Multiprise mainframes are each managed by an IBM ThinkPad that is never powered off. The ThinkPad is "stored with its lid closed, held in a clamp upright inside the Multiprise cabinet. Those laptops are intended to be left on indefinitely."

· More on refilling printer cartridges (March 7): Samantha Steyn says her company is now importing "amazing inkjet refill kits" that use "cartridge-specific inks and incredible patented tools that make the refilling process really simple".