Thanks for your quick response!
Ok, I appreciate your advice. If the problem keeps occurring I will switch back to the latest stable.
But, still something strange about it: I had absolutely no problem the first weeks i was using this nightly (262 was since November 2011 the latest nightly until today), the problem started to occur from one day to the other.
I am using the radio version since probably half a year or even more, without any problems.
Also, 262 was reported (cyanogenmod forums, other forums) to be very stable on the Desire, almost no people reported having problems with it. That's why i decided to update to build 262. I for my part am suspecting a software being the cause for the freezes, but i have no clue which one.. I even checked the system logs.
As for the kernel: Call me a noob, but how do i change the kernel? I know how to root devices, flash recoveries and roms, but how can i change the kernel directly?