I was a bit concerned that M1ABD-3 was not performing as it should, so yesterday I went to Headquarters and checked the SWR on the aerial. There did not appear to be any problem and the SWR was 1.5:1. When I turned the computer back on it started to boot, but just as Windows was starting, it flashed up a BSOD and re-booted itself. It kept doing this over and over again and the only way to stop it was to turn the power off. The BSOD flashed up too quick to read, but I thought it must be a disk problem.
So, I connected up the spare computer and brought the broken computer home.
I booted up into the Recovery Console and ran CHKDSK. After whirring away to itself for some time it reported no errors on the disk. So, fingers crossed, I started the computer normally and it burst into life again.
Can only assume that the disk must have had a problem and CHKDSK sorted it out.
Back to Headquarters tonight to replace the computer.