Sometimes computer telling me c drive is full.

If you’re hard drive is too old and it has a small space. In that reason your primary hard drive full or it has not enough space in c drive. For this problem you can delete some unrequired files from your C dive. Sometimes when your hard disk had a good number of bad sectors it may seems this type of message.
For this you can try to run it by defragging. If it failed to run your hard drive you need to replace it. If don’t replace the hard drive you can add a new hard drive with it. Then you can save some additional data in your new hard drive.
Thank you.
You will need to do the following to make that your C drive is indeed not full as the error message tells you:
Clair Charles