I assume that you also have a C: Drive.
How much free space is on the C: drive?
The low amount of free space on your D: drive may or may not have an impact on your system freezing.
Does the D: drive have data files?
Program files?
Backup files?
For the C: drive, there are a number of things that we can recommend.
For your D: drive, we really need to know what is on the drive before we can offer good suggestions as to what you can safely remove.
General guidelines for files that you can remove:
C:\Windows\Temp
Any file over 2 weeks old is safe to remove.
Open your web browser (IE, Netscape) and clear the disk cache or temporary internet files.
For IE, click on Tools, Internet Options.
On the General tab, in the Temporary Internet Files section, click on Delete Files.
Clean out your old email messages.
Old data files that you either don't need or have good backup copies of can be deleted.
Another thing you should try is to download and run AdAware from www.lavasoft.de
This program helps you get rid of spy-ware and ad-ware that some websites and "free" software installs on your system.
Chas