Windows Explorer has stopped working (AppHangB1 or AppCrash)

My windows explorer stops working constantly - I can't move or delete files,
which means that my hard drive is now completely full, meaning the computer
is useless. I have backed up my files, but as I can't delete them I can no
longer work on it. According to Microsoft, Toshiba is responsible, as they
sold a 'bundle' of software to Toshiba. Toshiba say the software is
Microsofts and therefore it is a Microsoft problem. They suggest I delete
and restore the whole system. But I can't because I have purchased other
software which I will lose if I do so. Where do I turn next? P.S. Every
time it says it will find a solution on line, but it never does.

If you purchased other software, you should at least have it on Installation
disk or be able to back it up to something, blank disk, external drive and
then reinstall the OS.