Ubuntu :: Sometimes Crashes During Boot?

I have a weird problem. Sometimes Ubuntu freezes when I'm booting up, sometimes not. I would say 2 out of 3 times it crashes, all other times it goes fine. I alway get past the GRUB bootscreen, then it starts loading. Towards the end or so, all of a sudden all disk activity stops and the screen hangs. Ctrl+C, Ctrl+Z, Escape, whatever buttons I press, it doesn't do anything.

I removed the "quiet" and "splash" boot options in GRUB so I could see in detail what is loading, but this doesn't make any more sense then before. The lines of text are always a bit different every time it happens so I can't really pinpoint when it goes wrong. Anyway, I don't see anything wrong with the output on my screen, I guess the real problem is not displayed.

I also tried booting into recovery mode. Also here this is strange. Sometimes I make it to the recovery screen with the options (resume, clean, netroot, ...), sometimes it crashes before that. When I get the recovery screen I choose "resume", this usually works and then I use "startx" to go into graphical mode. However, at other times, when I choose "resume" it freezes even before I get a login prompt.

So please guys, tell me, what is the problem here? How do I find out where I should start looking. Ubuntu sometimes freezes and when it does it doesn't alway happen at the same place as before. I know only 1 thing for certain, once I'm fully booted I don't have any problems whatsoever, everything seems to work flawlessly.

I am running a dual boot system with Ubuntu 10.10 and Windows7/XP. I am running kernel 2.6.35-24 (also tried 2.6.35-23, but no difference). I have an i5 CPU, so 64 bits. If you need any more information, just ask.