Imac core duo early 2006- snow leopardConstant freezes

Hi everybody,
Been having a very frustrating problem with my Imac 2in early 2006 core duo,
IN the last couple of days or so anytime I start any app for no apparent reason and randomly with no hardware noise connected to it, the system comes to a sort of a halt,
Cursor can still be used but only to navigate screen and not to select anything.
No response from the system is detected for approximately 35/40 secs up to a minute.
In several occasions I had to force shut down system as no action could be taken.
I followed certain links on the net regarding hdparm ans such and issue with hard disk parameter. added a util found on the net on to /usr/share directory
then rebooted system and it seemed to have helped for a while but then issue resurfaced.
Decided to test external usb 2 lacie 1tb hard disk for faults (used for time machine backups) therefore disconnected unit and worked without it for a while.
It seemed as if the problem was solved but once again issue resurfaced.
I then re-installed snow leopard keeping all programs but it did not help.
Therefore did I clean install and then re-installed apps from time machine backup.
i am now in the process of buying tech tool 5 to check for possible hardware problems.
In the meantime:
has anyone come across such problem???
And if so what troubleshooting steps have you taken.

cheers

Mirco

This particular issue is most often a dying hard drive. It could also be due to just a full hard drive. How much free space is on the system drive after restoring from your back up?

I've had brand new drives that would allow a clean install, but then basically lock up when you tried using them (and on Win systems).

After a restoring I had approx 150Gb/160Gb considering that I have Logic 9 and other software installed.
I have an external usb 2 lacie 1Tb hard drive that was originally partitioned and I have now restored to a single partition and it seems as if the problem is gone for now.
fingers crossed, touch wood.
Ran loads of tests on internal hard drive win tech tool and no probs were found, goin to run apple hardware test later to check again and in the meantime im creating an edrive with techtool which I will use later to diagnose.
Where can I find a cheap dvd drive+hard drive for this model?? in case??

Still experiencing same issues, more moderate than before as I have not had any complete freeze that forced my to force shut down computer.
Looking to buy a new hard drive anyone could point me in the right directions??
And how difficult is it to replace it??

First, do not cross post or post an additional message of the same subject. Always post back to the original thread.

Best place to buy hard drives on line is from OWC.