Great advice from all of you. I'll try to answer everyone's questions:
Both PCs are running XP. These files are shared over a Win2000 server; however, the two of us who have the problem are not using the same files. Therefore, after reading the last link from microsoft support that bcastner sent, I think that is definitely the problem. I ran the Trend Micro anti-virus check and it came up clean. The PCs are both current on updates and patches and are regularly degragmented. I do have a problem with the server though in that I cannot run the updates and patches on it. I get access denied messages and no patches will run. That issue has to be resolved before I can fix this current issue. This is not the right forum for that problem, but if you happen to know the answer to that one, I'd appreciate it!! I have full administrative rights. I printed some information bcastner wrote in another thread about unregistering the old control. I haven't done that yet. If that's the answer then I'll try that. You've been so helpful -- all of you. Thanks!