Had a Virus, Slow Startup and has "I/O error status 0xC0000185"

Hi,
Follow the suggestions and see if it helps.

Method 1
You may run a complete virus scan.
Microsoft Safety Scanner
http://www.microsoft.com/security/scanner/en-au/default.aspx
Note: The Microsoft Safety Scanner expires 10 days after being downloaded. To rerun a scan with the latest anti-malware definitions, download and run the Microsoft Safety Scanner again. It also performs check disk and you may lose amount of data.

Method 2

Check if the issue exists in a clean boot state.
How to troubleshoot a problem by performing a clean boot in Windows Vista or in Windows 7
http://support.microsoft.com/kb/929135
Note : After troubleshooting follow Step 7: Reset the computer to start as usual 

Method 3
You may run Check disk.
Check a drive for errors
http://windows.microsoft.com/en-us/windows7/Check-a-drive-for-errors
Note: When you run the check disk, there are chances of losing data so you can take a backup of your files before running check disk.
 
Method 4
You may restore the computer’s settings to a date when it was working fine before.
System Restore
http://windows.microsoft.com/en-US/windows7/products/features/system-restore

Also see:
Optimize Windows 7 for better performance
http://windows.microsoft.com/en-US/windows7/Optimize-Windows-7-for-better-performance