We are starting to see a problem with some Windows XP machines. These XP machines are running unpatched, vanilla installations of XP. They are not connected to the internet and so haven't downloaded any updates, no software is being updated. Our application runs fine when the system is first used but over time the performance of the XP machine is slowing down. By 'over time' I mean the PC itself is running for weeks without a power cycle and the application we've built runs for days at a time. We have only just noticed this slow down because the XP machine has a life-sign protocol with the rest of the system which is not being triggered because the load on the XP machine is too high, failing this life-sign halts the system (if you've read some of my other questions you'll know the system counts cash and so it's important that records are kept of how much cash has been through the system, which is what the Windows XP machine does).
So, does anyone have any ideas why the XP machine is slowing down? Is it the system event log, an unnecessary service or something else. Any ideas how to identify the source of the slow down?
Edit: If it were up to me, I would update with the latest patches. Unfortunately, these PCs are in banks based in other countries and they really don't like the machines being updated, let alone being connected to the internet. I have two options for investigating the problem: 1. Ask a field service engineer to get information from the machine and 2. flying out to the machines and seeing what's happening first hand. Option 2 would make the banks suspicious, which would be bad (we have a work-around at the moment, but we still need to work out why it's happening and whether or not the fix will last).
Finally, the people using the machines do not have access to the explorer shell, there is no start menu, alt-tab and ctrl-alt-del are disabled (again, the banks don't want anyone having access to the data/software).
We've asked w service engineer to get some data from task manager and do some defragging (although I'm not sure a defrag will do much).