Problems after installation with frequent locks

[Antonio M]

I am helping a friend of mine to set up his machine with Fedora 12
1) we installed by DVD and it was o.k
2) after rebooting we set up the user
3) we started to upgrade with latest updates (but at the moment we
have not yet upgraded kernel) with Package kit
4) we are experiencing system locks very often
5) we are using an AMD system with 2 Gb of Ram and an ATI graphic card

if after kernel updating shall experience such locks, what shall I try??

The computer is working great with Windows, so we discarded any
hardware problems.

Tnx

-- 
Antonio Montagnani
Skype : antoniomontag
SIP: antoniomontag at ekiga.net