Hi again,
Well, after about 18 months of constant crashes, reinstalls, more crashes etc, etc, I think my problem is finally sorted. However, I still don't know what the cause was.
The MC server was running Windows 7 Professional and was kept up to date with all the latest Windows updates and MC releases. Over the period of the problem I have reinstalled Windows and MC multiple times, changed various components, checked memory etc all to no avail. Anyway, seeing as the expiry date of the free Windows 10 upgrade was drawing near I decided to do the upgrade if only to get the machine registered and then revert back to Windows 7 if needed.
The Windows 10 upgrade went smoothly and since then I haven't had a single crash and the upgrade was done 6 days ago whereas before it would crash multiple times a day.
So I still have no idea why it was crashing all the time but I am overjoyed that it appears to be sorted now. I'm still working through a few annoying things about Windows 10 but nothing too problematic.
Fingers crossed this is now permanently fixed.
Russell