Possibly not a virus?
Although this could indeed be the work of a virus, it may also be a form of copy protection.
Do these disks with that checksum error on actually use that sector for any important data? It could be that the publishers put a deliberate error on a sector which isn't needed by the game purely so if someone tries to copy the disk, most copying programs will say "checksum error on track 0" and abort the copy.
The smarter programs would either automatically repair it or just copy it with the incorrect checksum.
My guess would be this situation occurs on the oldest games from around 1988 when people used to copy disks with the Workbench Disk Copy command. This deliberate error probably prevented that from working, thus possibly increasing sales of the original a bit.
The other thing to consider is if the game in question uses it's own MFM loader it can happily ignore all the checksum information and load the game anyway, knowing that it won't match. The checksum is only used by AmigaDos to verify the file is OK.
I assume from the investigation done that it does stuff up the games so they don't load, otherwise you probably wouldn't bother to post here.
I could be completely wrong of course and it maybe a virus but it seems to be a pretty stupid virus if that is all it does!