This is probably the trickiest issue I've ever come across so lots of good karma coming your way if you help me resolve.
OK, we have 4 notebooks in a network, all of them are different hardware spec, bought at different times.
They all keep freezing intermittently. I don't just mean a crash, I mean they just freeze, no mouse activity, no warnings, no error messages in event log. The only way to recover is to power off the machine and reboot.
They share this in common:
-Run Windows XP SP3 (recently updated from previous service packs)
-All connect to a Windows SBS Server 2003 (the server was recently upgraded but the issue began over a year ago)
-All run Office 2007 (recently upgraded from 2003 but the issue existed before this)
-Running McAfee Antivirus (but the issue was occurring prior to this, before this they were running Trend Micro)
The entire network is new, as we began to suspect the problem was network related, so we replaced the switch, router and server earlier in the year (after the problems began).
We've removed all common software that they don't need such as an instant messaging program that they all used.
The freezes happen randomly, though recently i've been advised it tends to happen when saving a document such as Excel or Word.
The freezes happen both when they are inside the network, or externally, though it's not established if they are connected to the VPN at the time.
2 of the machines were completely replaced under hardware warranty, our initial thought was this is probably RAM but that's not the case, as all have had the RAM removed and had new modules installed from a different source.
Lastly, the issue is now happening to a brand new machine that has only been introduced into the network in the past 2 weeks.
As you can see, this has been an ongoing drama for some time and it would be brilliant to know if anybody has experienced and resolved a similar problem before.