Speedsys seems to be used a lot around here to benchmarks older systems. I started using it recently and noticed it wipes out and corrupts the contents of a ramdrive created with the popular Xmsdsk.
Create a ramdrive, doesn't matter what size or options you use. Copy any files to it or however you would use it. Run speedsys, exit it and change to the ramdrive. All files will be wiped and the label name of ramdrive corrupted.
Took a while to narrow this down to speedsys, as it gave the impression and I wasted lots of time being certain it was caused by bad ram sticks.