It sure sounds like there is a potential problem with the hardware. Just because you can see the lun and get to the folder doesn't mean there's a problem. There could be a write problem that isn't affecting reads for example.
Check the SQL Server error log. If you see any 823 errors refer to the following articles.
I'd always get the hardware vendor to check for hardware failures. The fact that the error message indicates that there is an IO error indicates that this is where the problem most likely lies.