Sometimes Windows Firewall can produce that error, so see if turning it off helps.
Also boot up into the advanced boot options and select Repair your Computer, making a note where it locates the OS.
Select Command Prompt and enter bcdedit |find "osdevice" to confirm the partition letter then enter chkdsk x: /f where x is the partition letter.
This will execute a chkdsk without the need to reboot.
Type and enter exit to close the command window when done.
If you have an install disk that includes SP1 then you can boot up with that and navigate to the Recovery Environment to select Command Prompt to do the same, but you can also execute this command - (assuming c is the partition letter)
sfc /scannow /offbootdir=C:\ /offwindir=C:\Windows
For clarification, that is a Pipe symbol before find which is the upper case of \ and in the sfc command, there's a space before each /
