An explanation is at http://www.howtogeek.com/howto/windows-vista/working-around-windows-vistas-shrink-volume-inadequacy-problems/ .
I have used Acronis Disk Director on this Vista system and have never experienced any of the dire fates you allude to in your post. Just remember: Before undertaking any disk resize, merge or other such operation, whether it be with Disk Director, a freeware tool such as GParted or any other such software, backup any files you can't afford to lose to CD/DVD and defragment the drive you're working with.
Hope this helps,
I got this problem in both my desktop and my new laptop.
In my desktop, the drive C has 130G in totle, system files and data occupies 50Gb and there is 80Gb free. But when i go to the disk management and right click the disk c to shrink it, it only allows me to shrink 4G. How so?
My new laptop is even crazier. It has a 320G hard drive. The dirve c have data that acounts for 50G, but vista only allows me to shrink 120G, and occupying 160G that is more than three time larger than the size of the system. And this is a brand new computer, I haven't installed my softwares yet and barely use it.
According to my research on the internet, I turned off the system backup, and delete the so called pagefile, delete temporary internet files, and it can only free about 14Gb in my desktop.
What is the problem? Vista is driving me crazy. I heard someone saying Vista does not allow repartition of the size larger than 50% of drive C. Is this true? Third party parition softwares such as acronis disk director 10 is recommended by some but there are also warnings by others that this might cause the system to collapse. So I am very confused as of what to do. I really need to free more hard disk space for sure. and I do have acronis software. but i do not want to disable the system.
Can anyone give me some help?