Harddisk kliks -> System freezes/reboots

[Rolf Gerrits]

My harddisk says "klick" ( parking I presume ) for no apparent reason ( 
that I can think of ) and my freezes or reboots.
I cannot find any hints in the logfiles what causes this.

I need some hints / suggestions where to look / test I can do / .... 
before I buy a new harddisk.
.... I am going nuts with this....

Info:
1. just my desktop ( gnome ) will crash after 1-2 days
2. if I reset - due to a freeze - sometimes the harddisk says "click" 
BEFORE Grub starts (sits on MBR) .
3. This started after I installed GKrellM (could be a coincedent) .... 
removing GKrellM did not solve anything (maybe broke something ? )
4. I removed "hddtemp" and "cpufreq" services ( the latter won't work 
for my hardware anyway ... so it says )
5. I have removed some corrupted files and my harddisks are free of 
badbloks or things like that.

HELP !!