Is the file g2mdlhlpx.exe a threat or is it normal in Vista?

hi

to be sure your computer is clean scan for Malware

download update and scan with the free version of malwarebytes anti-malware

http://www.malwarebytes.org/mbam.php

you could also download and run rkill to stop the problem process before downloading and scanning with malwarebytes

http://www.bleepingcomputer.com/download/anti-virus/rkill

if it does not remove the problem and or work correctly in normal mode do the above work in safe mode with networking  

Windows Vista

Using the F8 Method:

1. Restart your computer.
2. When the computer starts you will see your computer's hardware being listed. When you see this information start to gently tap theF8 key repeatedly until you are presented with theWindows Vista Advanced Boot Options.
3. Select the Safe Mode with Networking option using the arrow keys.
4. Then press the enter key on your keyboard to boot into Vista Safe Mode.
5. When Windows starts you will be at a typical logon screen. Logon to your computer and Vista will enter Safe mode.
6. Do whatever tasks you require, and when you are done, reboot to go back into normal mode.