About 3 weeks ago my laptop got the worst virus infection ever, with the tenga.a virus http://forum.kaspersky.com/lofiversion/index.php/t7172.html and http://www.f-secure.com/v-descs/tenga_a.shtml It was much worse than the infection I had 14 years ago with One-Half, which slowly but steadily encrypted cylinders of my HDD. The tenga.a infection has shattered my mistaken belief that Win98 is not vulnerable to infection anymore, in 2010. Tenga.a came out around 2005 http://www.viruslist.com/en/weblog/167434325/Classical_viruses_ITW_never_say_die Tenga.a infects most .exe files it can find. It has infected all FAT32-based Win98/2k/XP operating systems on my multi-booting laptop. Only one operating system/partition, an NTFS-WinXP rarely accessed, was not infected. The most serious damage was the infection of one 192GB partition of an external 1TB USB HDD, which contained about 100GB of software downloads + installable programs, many not backed up because it was a work disk. I became aware of the tenga.a infection maybe after 5 hours, when I noticed that the disk access light kept showing activity, even when I was doing nothing on the laptop. But then it was too late, the infection had spread across operating systems/partitions, also to the attached USB HDD. I still have no idea how I got the virus, with maybe a thousand .exe files infected. Maybe it was my bad habit of double-clicking even on suspicious files in a special test windows, and then restoring a clean test windows. Double-clicking on an infected file may have initiated the infection of a .exe on another partition, of another operating system, and started in this way an infection across operating systems. Getting the laptop clean again was relatively easy, I had to restore all partitions/operating systems/directories from backup onto a clean virgin HDD. The major problem was to recover the infected installation sources on the USB HDD; some of them may have been lost for good. Here some lessons I learnt from this infection: 1) Virus infection is still a real danger under Windows 98 2) The only defense against viruses like Tenga.a, if using only occasional on-demand scanning, is a very good backup and recovery procedure. 3) Don't rely on USB HDDs as a backup storage media of software because of their vulnerability to virus infections 4) Backing up installation sources onto write-once media (CD-R, DVD-R) is still an absolute must 5) Installation sources should always be backed up also into an additional .rar or .iso file, which are not as easily infected as .exe 6) It is very important to document the actual download locations of software, in case it has to be downloaded again 7) About 10% of my time with the computer is spent creating, archiving and deleting backups. This is time well spent and has saved my neck already a couple of times. 8) A spare blank HDD, of the same size as in the computer, also comes very handy if a complete HDD has to be restored from backup 9) Maybe I should look again into UDF-formatted HDDs, as supplementary backup devices which can be set to read-only and are therefore not vulnerable to virus infection.