Barring mechanical failure (like a fan stopping), or say the heatsink falling off, you're not going to damage a CPU just by keeping it busy.
However, here are a few things to try (I take it you're using IE from your other recent posts).
- clear the browser cache, and set a lower limit (say 20% max of your current FREE disk space).
- clear the browser history, and set a lower limit for the number of days to remember history.
Other system maintenance things
- are you fully patched with the latest hotfixes and service packs
- when was the last time you did a backup
- when was the last time you defragmented the disk
- when was the last time you pruned out old programs and data
- when was the last time you did a virus / malware scan
I'd like to take up Salem's last item - virus/malware.
Before doing that, what happens if you get to hotmail via the Mail tab on MSN.com?
If you have a malware that hijacks requests to hotmail,.com, that might be an answer. Never heard of that particular trojan, but, you never know.