Hello Laharl

Welcome to PCHF
I apologize for the delay in response.
I would doubt it is a hardware problem since you are at least getting into Vista but just not showing the desktop. Does it at least get past the Vista splash screen and welcome screen? Or does it just show a black screen during the boot process and you don't even get to see the beginning of Vista?
Do you have a lot of important data you would fear losing if you did a full restore of Windows?
If you aren't even getting to see the Vista splash screen, then you can try running Memtest (click my link below, free download) and a hard drive diagnostic which you can download for free from the manufacturer of your hard drive. Both tools you will make a bootable CD or DVD with and boot to it then run the utility. The diagnostics will test your memory and hard drive for problems.
Let me know a bit more info and we can go from there
