I get the following as a message on the Windows EXploere screen:

"MS Visual C++ Runtime Library

PrgramC:\Program Files\Internet Explorer\explore.exe
This application has requested the Runtime to terminate it in an unusual way.
Please contact apps support team for more info"

It resists closing and at the same time locks up the PC. Have to re-boot every time to clear it. Anyone know what is going on here, please?

Sounds like some odd quirk in one of the dlls used by Windows Explorer. Could be a corrupt file or a virus.
Try running sfc /runnow to check the Windows system files.
I would also do as advised and report the error to Microsoft, in case it is a programming error.