Task Manager will not end a process?!!

Hi there... I get this now and then and it is really annoying. It happens the most with Firefox internet browser but I also get it on other things. Basically the program hangs and then I can not kill it off the task manager.

Now win7 "can" do it cause if i reboot it kills it before rebooting...

I have tried KILL PROCESS and KILL PROCESS TREE in Task Manager, Microsoft Process Explore, Pskill.exe (run form cmd run with administrator) and taskill.exe (run form cmd run with administrator)

Juts reboot you say? Well I am on a work system and we run complex calculations to mine for statistical information. These calculations can take days even, and I can not reboot or log off my system during this time.

Please help this is really frustrating and also pretty important.

Thanks in advance

I've run into hung apps only to find I can't whack em.
Its insane that we dont have that user control anymore (regardless of rights)
I've tried any number of tools/methods to kill hung apps. No dice.

Win7..with a hung/crashed app...brings back the days of windows 3.1.
Task/process hung up? Just reboot!!
Way to go MS!...ya pinheads!

Yeah, could not agree more. How is it with this latest, greatest OS we took a giant step backwards in process handling. Oh, sure, there are a ton of nags that come with everything now that you cannot get turned off (such as the normal operation of sending an encrypted email having the OS ask you for permission to use your certificate to encrypt the email.. but always defaulting to 'deny'). But to now not be able to kill a process? Come one. Unix had this in the bag in the 1970's.... and now windows is back to where it was in the 1990's... which is way worse than Unix of the 1970's?