Registry Cleaner Removal

When cleaning my Registry on my PC with CCleaner, it always fix all the registry keys except for 4 of them. And it is always the same ones that stays unfix. The CCleaner says:
Invalid Default Icon
Solution: Delete the Default Icon registry key.
Solution: Delete the registry value.

i would not reccomend deleting registry keys unless you know what your doing but if you click the start bar and then run and type in "regedit" (without quotes) all registry keys are in there. if you accidently delete a reg key that stops your computer from running properly then you will have to do a system restore by entering safe mode and clicking yes when asked if you want to system restore.