There is nothing that would remain from a previous copy if you have rebooted. There is something else wrong. You are pointing fingers to something that is not related.
A side note, why are you using IE7 on Vista, or anywhere else, for that matter? IE8 is a quicker, better, more secure browser. (I am sure others will soon chime in and tell you to now ever use IE any version, I won't. I like IE. But I would update to IE8. Not that has anything to do with your current problem, though.)
I have a 2.5 year old Dell Inspiron 1520 running Windows Vista Home Premium using IE 7.0. Suddenly, I cannot cut/copy paste. Something I cut/copied earlier gets hung up and it is the only thing I can paste. The only solution is to reboot. How do I fix this?