Steam eats memory

I think I've posted about this before on this forum but I've not managed to solve it. On Steam when I run the game files defrag or 'verify integrity of game cache' my memory usage shoots up to 100% and the computer locks up. I've posted some screenshots to show what I mean (I stopped the verify before memory got to 100% and I only opened task manager a while after I started verifying which is why the blue line starts high then ends straight). I have no other programs running and before I opened steam, mem usage was around 1 gig. I've also tried disabling some background tasks to see if I could find any incompatibilities and when I disabled KIS, the problem stopped. I re-enabled it then disabled just the Files and Memory protection component and the problem didn't occur. When I re-enabled it it happened again. Any idea why this is happening?
http://f.imagehost.org/t/0841/steam_bug.jpg

Steam is making lots of small reads to a large amount of data. If you intercept each and everyone one of them and scan them before continuing you're going to very quickly saturate I/O and if it's placing a copy of the data in memory to scan it then it's going to very quickly overfill.

To stop your computer locking up increase your virtual memory size to that greater than the size of your steam files.. but it'll still go really slow. You really need to exclude your steam folder from the on-access scan and just make sure to include it in your regular system wide scan.

never had that problem with using that feature, I would check the appropriate Steam forum, most likely there will be a user with the same issue.

Careful you find the right forum and not TF2 or L4D forums, otherwise your IQ may drop several points.

My swap file is ~10GB and I have 4GB of physical memory. People can run this check with 1GB of RAM and maybe 2 Gigs of swap space so I doubt it's because of a lack of memory (I agree I think it's because of the on-access scanning but surely other users of Steam also have AV). I should also mention the memory is not released until I completely exit steam. And when I look in task manager, nothing appears to be using that amount of memory (although I haven't yet checked in performance monitor) and even when the memory is saturated, around 3 gigs appears to be 'cached' (check screenshot) even though the physical memory usage line claims otherwise - the amount cached doesn't normally effect usage as I think that can be released easily to the system.
Does anyone else who uses KIS also use Steam? Does the same happen?

Thanks for your help :) I'll make a post on the Steam forums also.

have you tried using the beta steam client?

That's an idea, I'll give it a shot later. How do I get it?

There is an option in the client somewhere to show what beta orpreview programmes you are signed up for, if you go into that you can select the steam beta.

Sorry I can't be more specific but I did it a few weeks ago and I'm at work at the moment.

File --> Settings

Under Beta Participation click Change

Thanks. I'm not using that PC right now and I thought it might have involved something more complicated - some betas I've tried in the past required config file mods or manual downloads.