Try uninstalling clearing registry and then installing. If that doesn't help clean instal of windows again will help. But truly you should work on newer software. SW 2007 wasn't made for windows 7 and i believe its 32 bit on 64 bit system. All of these are not big problem becuse it still worked , but truly there could be so many possibilities. Your company should do some upgrades. First get some better machine, newer solidworks, and for one you wont have problems as it will be vendors resposibility that everything works plus SW will be faster on better machine. Or atleast add some real graphic card and more ram. Your integraded graphics use your ram which is mostly used by system.
What has changed on your system since a week ago?
What Windows Updates or other software updates have been done on your system?