"The daughter's PC not been quite right...."
Not quite right in what way would help.
Generally with older systems, I would start with a good cleanout, malware scan, and update.
Clean redundant files from the hard drive with Wise Disk Cleaner click here
Clean the registry with Wise Registry Cleaner. click here
Download and run Malwarebytes and Spybot Search & Destroy. click here click here
Ensure Windows updates are all installed.
Ensure drivers such as the graphics card driver are up to date.
Defragment the hard drive.
Only then do I start any troubleshooting, as many systems behave themselves after a good cleanout.