Question : Folders cannot be opened

From time to another I have folders, that cannot be opened.
When trying to open a folder(in MyComputer) it takes 3-4 minutes before I get a question:
C:\ drive is not formatted, do you want to format now?
And I am not able to delete, rename or anything else with this folder.
What is the reason and what can I do about it?

Answer : Folders cannot be opened

First take a backup to be sure you'll have everything.
Then do a check of the harddisk (windows explorer - rightclick C: - properties - tools - check now.
What kind of disk (what brand) do you have?