Hi and welcome
Are you using a Wacom graphics tablet?.....if so try removing the Pentools plugin as this plugin is known to cause a number of hassles for people
What other software do you have installed?....ie plugins etc?
Also do you have the ATM plugin?,thats another known nuisance
If you are using the automatic software update panel to upgrade your extensions etc be aware that it can upgrade something that will not agree with something else which has to date been working fine.I do all mine manually
Cheers
Stu.