Cursor & System Freeze - Vista

I have two problems with my Vista Home premium system running on desktop (HP Pavilion - 32 bit):

Recently the mouse has frozen in place while on the net, and simultaneously the light
next to (right side of) the On/Off light goes out. Ctrl/Alt/Delete does nothing. I have to do a hard shut down. System then works normally for a brief period until
the freeze reoccurs.

2. Thinking this might be caused by a recent update, I attempted to turn the system
back about a week, using System Restore. Online instructions indicate that I should have the option of choosing an earlier restore point than the only one given, which is
today's date. I entered a date one week earlier, but it reverted to today's date.

I've run Avast virus scan and Windows Defender scan with negative results.

Can someone please point me in the right direction?

Basic System Check under Reliability & Performance: Failed - Drive D has 14%
disk space (1197 MB) **** What do I do about this?

Thanks so much for any help to get this situation resolved.