|If you boot to Safe Mode, you'll be able to login with the default Administrator account and check the permissions of your normal login account. If you're getting access denied on the System32 folder (not Registry), then your normal login is probably not an Administrator.|
You can't just tell the machine to reformat. I'm not sure if Compaqs have a Recovery Partition, but you could check HP's website. If not, you'd need the OS CD that came with the system to reformat and reinstall the OS. You'd lose all your data, so you'd want to back that up first.
"So won’t you give this man his wings
What a shame
To have to beg you to see
We’re not all the same
What a shame" - Shinedown