You may need to remove permissions from the parent. I would remove all permissions from the troublesome folder, then grant everyone full control over it and it's children - this should ensure you can rename it, and also that any odd permissions from the parent aren't being inherited.
- Right click on the folder, and select properties
- Select the security tab.
- Click "Advanced"
- Click "Change Permissions"
- Untick "Include inheritable permissions from this object's parent"
- You'll be given a notice regarding permissions - Click "Remove"
- The permissions area is now blank. Click Add
- Type "Everyone" and click OK
- Tick "Allow" next to full control.
- Click OK
- Back at the advanced window, you should only see "Everyone" now
- Tick "Replace all child object permissions with inheritable permissions from this object."
- You may also want to change the owner here.
- Click Apply. When warned about the permissions being overwritten, click Yes.
- OK your way back to Explorer.
You should be able to now make changes to the folder. You may also want to ensure the folder is not read only as this can sometimes happen (and the unset read only won't be kept until you make these changes to the permissions)
These instructions were written under Windows 7, but should be reasonably accurate under Vista. If you need more information or screenshots, let me know.
Hope this helps.