So is the problem with your D:/drive? Is this the drive you use for your CD/DVD's? Is the door/drawer working properly?
You also say that your system is not shutting down properly. Are you getting any errors and if so, what does it say?
Are you having any other problems with your machine?
1. What version of Avast did you install? 5.0.677 is the current version.
2. What product of Avast did you install? Free, Pro, AIS?
3. Are your MS Updates (if you have Windows) current?
4. Are the Avast definitions (updates) current?
5. When was the last time you did any kind of scan in Avast, and if so what kind of scan was it?