Greetings,
The first thing that you should try is to perform a mass compile on the lvdsc folder of LabVIEW. This can be done by opening a VI in LabVIEW, navigating to Tools>>advanced and selecting mass compile. In the dialog window that opens, navigate to c:\program files\national instruments\labview 6.1\vi.lib\lvdsc and click the button to "select cur dir". On the next dialog, click mass compile. Hopefully this will correct the exception that you are receiving.
If not, there may be corruptions in the VI's or there is possibly duplicate copies of the VI's on your harddrive. Either way, there is a VI called lv_init which loads the DSC VI's, so if there is an issue in any of the VI's you will see that exception again.
At that point, I would recommend
performing a reinstall of the DSC module. After completing the reinstall, Launch LabVIEW before installing any of the fixes. Then download our most current fixes from our website.
http://digital.ni.com/softlib.nsf/websearch/513AA4A0BB60D10086256B48006D44B5?opendocument&node=132070_US
This should take care of the issue. Have a good day!
Patrick R.