Okay - first of all in the future you need to tell us everything in your first post. All of this information is important in troubleshooting.
The error you are getting is most often caused by either new hardware or a problem with a driver. From where did you obtain the drivers (laptop drivers should always and only be obtained from the website of the laptop manufacturer). If you got them from anywhere other than the Dell website, you need to replace them with the Dell drivers. The way to do that is to go to the Dell support website, enter your service tag number, and download and install the appropriate drivers for your system.
You said you reinstalled the OS. Since it was a new hd, you couldn't have done that from a recovery partition so I have to ask two questions: First, did you install the same OS as was originally installed when the system shipped? And second, did you use an original, retail OS disc or a disc provided by Dell or something else?
And last, since MS Office seems to be involved are you using an original, legitimate copy of Office?