Computer freezes

[jaws40]

Since I have installed XP, I have noticed two things.
1. The computer freezes when left on without any
activity for more than 15 minutes. The only way to
resume seems to be to turn off the machine and turn it
back on. Is there some other key I need to depress in
order to resume?

2. I use a dial up connection to get to the web. I have
noticed that sometimes the modem does not fully
disconnect when I logoff from the internet. I have to
fully restart the computer, even though I have a dial
tone on the phone!

Can anyone offer any suggestions?

Thanks kindly

Jaws40