Here are some things you could do to troubleshoot:
0. Google this issue. There are a bunch of people with similar problems.
1. Reboot your computer
2. Cut and paste the simplest possible thing (maybe a single word from a web page). Does this crash word?
3. Cut and paste items from several different web pages. Do they all crash word?
4. Cut and paste the same web page from FireFox, Chrome or another browser. Does it still crash?
5. Copy some text, open word and from the edit menu chose "paste special"=>unformatted. Does it still crash?
Have you applied all updates to word and office? What version of Windows are you running? If xp, goto update.microsoft.com to enroll to get updates for all MS products, not just windows. Then check for and apply all updates. (In vista or windows 7, there's a link on the update screen next to the "You receive updates" label that will let you do the same thing.)
6. Completely reset IE 8 settings: Control Panel=>Internet Options=>Advanced=>Reset
7. Uninstall and re-install IE 8 (if running xp).
8. If you run vista+, or run xp and have your original disk, run "sfc /scannow". This will examine all key system files and repair any corrupted ones.
9. Repair your office install (goto control panel, programs, select office and click change/remove. you'll be given the option to repair your install. original disk may be required.)
10. Run full malware scan with your virus scanner, and a free product like superantispyware or malwarebyte anti malware.