OK, First, Dell Tech support won't help you with a virus, or a suspected virus. They will refer you to Norton, or whatever they push now. Second, what operating system do you have. I have the Dell restore disks for Vista, XP, 98 and 95, if you have the SN# on the side of your case. Third, if the number of issues keeps changing you may be looking at a hard disk problem. That Dell tech support can help you with.
Norton should be able to fix all the problems, but you may need to run it from DOS ( remember DOS) You can make a Norton recovery disk for the older computers, not sure what they do now, maybe use a thumb drive.
If you really have 800+ infected files downloading to a backup drive will just move them. The only solution in that case is to "FDISK", "FORMAT" and "REINSTALL" . Then load an up to date version of Norton or any AV and bring the files back 1 at a time.
We did Dell tech support in Heathrow for years until they moved it to an unnamed Asian subcontinent, so I have some knowledge of the issue. You can contact me if you need at
gowens1@cfl.rr.com
gary