If you enter this string (part of the error message): Segmentation Violation In Task [ DATASTEP ]
into the search box at the upper right-hand side of the forum page (where there is a white box, the "Search support.sas.com" menu and an orange Search button), you will find many hits on this particular error message. Without looking at the data and seeing your code, it would be a game of 20 questions to even make a guess at what the issue is. And, in addition, it is hard to offer constructive help without understanding the full particulars of the operating system on which you're running (You say you're running SAS 9.1.3 -- but WHERE -- on Windows, on Unix (what flavor of Unix), on Linux, or on the mainframe??)
Your best resource for help with this kind of error would be to open a track with Tech Support. They can look at your data, at your entire program and at your log to determine whether any of the Tech Support notes is relevant to your issue.