Actually, this IS the spare mouse...it's doing exactly like the other one. Surely they wouldn't be malfunctioning in exactly the same way..?? That's why I thought it might be something else, something to do with my computer. But then, I've had to wipe and reload XP and it's still happening. Boy, THAT was a trip!!!! It took me fourteen hours just to load the operating system! When I finally got it loaded I went into the BIOS and found that the first guy I took the computer to had somehow messed that up...so I reset all the defaults and it's worked like a charm ever since...ummm, I'm sorry...I was talking about my mouse wasn't I?? Anyway, thanks for the input...I appreciate it...I guess I'll just break down and buy a new one...it's just hard to find one exactly like this one and I do love it so...LOL! I just don't like the original mouses anymore, since I got used to this one.....oops, sorry...rambling again! Thanks so much for replying!