Windows 7 Shuts Down Programes?

hope somebody might recognize the symptoms. last 12 months Been running windows 7 on a top range PC computer, 2 TB HD 16G ram ,2G Graphics card so the hardware is excellent, just recently when we get it to boot up sometimes its normal and boots up in a couple of minutes but others it can take an hour, when we open |word or other programmes like Serif Page Plus, etc it just to open it shuts the programme down, there's is way we can save anything as "Save As" seems to be a major problem. When we are about to shut down it come up with various programmes saying such and so programme has experienced a problem and had to close, even as far as saying that windows explorer had experienced a problem and had to close. Our gut instinct is its windows 7 , we have no idea what happened, we have two computers linked one is used solely for internet use the big one for data and Desktop publishing. We have manged to save all our data by going into windows explorer and sliding the data on to an external Hard drive..