Arrrrgh, so much for thinking it was sorted.
Machine worked flawlessly all day until I disconnected it to put it back under the desk and back to the same old trouble.
The diagnostic lights show a constant 3&4, which Dell explain as:
Memory modules are detected, but a memory failure has occurred.
They offer the following fixes:
If you have two or more memory modules installed, remove the modules, reinstall one module (see "
Memory"), and then restart the computer. If the computer starts normally, reinstall an additional module. Continue until you have identified a faulty module or reinstalled all modules without error.
If available, install properly working memory of the same type into your computer (see "
Memory").
I am happy working on the machine if someone would be kind enough to explain what the issue is, should it be an easy fix?
Thanks again,
BB