Attatch database - cannot browse to database
Just to eliminate access or permission related issue.... Check the following below:
**What login is running the SQL Service - For testing, change this to localsystem or a local administrator
**Are you running your SSMS with administrative privileges - If not run as administrator before connecting to your instance

Also try using other modules in SSMS that would require a browsing to a file and check if that works. For example, instead of using the attach option, test using a restore from backup. HTH