Without context, it's difficult to say what the problem is. However, there's a good question / answer over on
http://dba.stackexchange.com that covers the basics.
http://dba.stackexchange.com/questions/8986/could-not-continue-scan-with-nolock-due-to-data-movement To hit the highpoints here: * Large data set * `NOLOCK` query hint Some solutions: * change your code so it only retrieves the right data rather than do a full scan; * alternatively, change your code to do these big scans when data isn't being updated. * Another option, if the scans are just for (say) building reporting sets, is to offload that data onto another database, keep it up-to-date using Log Shipping or Replication, and read that instead.