Error importing package Asset

Error importing package Asset
How to fix?

Which package did you try to import? Are you on Unity Free or Pro? Which version? What operating system do you have?

Unity Pro 4.5.1/Windows 7 x64, any pack trying to import, and I see this error

Seems like you might either have run out of disk space when importing the package or you have some sort of file write protection set to the location you’re trying to import to.