Scrolling and Access

I have two questions related to a re-load of Win XP Pro after a “virus” infected my system:
1.) After re-loading windows, I notice that scrolling is very slow, it looks like the system “captures” a page and then displays it in “slow motions”. This did not happen before. Is there a scroll speed option that is perhaps set too slow?
2.) I cannot access “regedit” when I try to, the start-up screen displays and then immediately, I am logged off, goes away. This is mysterious as it worked fine before.
Any help on these two issues will be appreciated. Thanks in advance, Sid Kraft