XP loses connection to LPR printer after a few days

My mother is running Windows XP Home on her iMac (via Parallels
Desktop). She is experiencing an odd problem with printing from XP.
Unfortunately, she doesn't live near me, so I have a limited ability to
diagnose this problem.

She has an HP OfficeJet Pro K550 attached to her LAN at address
192.168.1.99 (i.e. TCP/IP printing).

After about a week or so, XP will suddenly complain that it can't
communicate with the printer. Other networking in XP works fine, the
Mac can still print, and other computers on the network can also still
print. Deleting the printer icon and reinstalling the drivers from the
printer's installation CD fixes the problem, until next time.

I would like a permanent solution. Like I said, I don't have access to
the computer itself, so I was hoping someone could give me specific
things to look for.