windows 98 cannot boot up,missing TDIM.S

I have an less than perfect work situation. A co-worker downloaded something from the internet and now cannot boot up Windows 98. The missing or added file is TDIM.sys.vxd. I tried to rename it so windows would boot up but to no avail. This is a troublesome problem since this co-worker is also my boss. Please if anyone can help.I do not know what it was she downloaded(won’t say).I thought it was a video driver problem but am not sure.
thanks for anyone’s help