Invalid VxD Dynamic Link Call

One of the PCs in our school system has error at startup “invalid vxd dynamic link call from VREDIR(01)+00005B12 to device 0487, serive 4. I work primarily with Macs and only have a little experience with Win9s5. I’ve tried reinstalling Win95 4 times with no luck. Before I result to reformatting does anyone have any suggestons?