ncReadMult errors periodically-no CAN DATA. Why?

[DECDEC]

I peridocially have no CAN DATA . Why? What should I do with the file made (excerpt shown below) and how do I get rid of the error?  I have the network set up to tramsmit periodically and using RTSI lines to trigger recognition of the frames.  Sometimes the error happens immediately...sometimes it occurs after many iterations.  Any suggestions because the nicanerr.txt file below does not provide me with the clue.
 
[DRIVER_VERSION_SECTION]NICAN.DLL_VERSION=2.1.0.0002NICANFRM.DLL_VERSION=2.1.1.0002DRIVERS\NICANPK.DLL_VERSION=2.1.2.3050NICANPU.DLL_VERSION=2.1.0.3008NICANTSK.DLL_VERSION=2.1.1.3002NICANCFQ.DLL_VERSION=2.1.0.3000NCVI.DLL_VERSION=2.0.0.3012NICAN_S1.NFW_VERSION=2010200NICAN_S2.NFW_VERSION=2010200
[CURRENT_SECTION]Section_Index=9[INDEX_0]Local_Time= 07/12/2007 17:57:03.916 Err_Status= Status:0xa0b55002-Location:0x20000000-Internal:0x00b55000 Function= ncReadMult[INDEX_1]Local_Time= 07/12/2007 17:57:03.916Err_Status= Status:0xa0b55002-Location:0x20000000-Internal:0x00b55000Function= ncReadMult[INDEX_2]Local_Time= 07/12/2007 17:57:03.916Err_Status= Status:0xa0b55002-Location:0x20000000-Internal:0x00b55000Function= ncReadMult[INDEX_3]
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[DECDEC]

Thanks for the reply!
a-Operation is at 500K.  Using two series-1 cards and one series-2.
b-Screensaver disabled, stopped application and did a self-test on all card==>passed.  Error still periodically present
c-Data may be blanked for with a few minutes for a few minutes until power cycle-.initialization and then not happen for many hours or problem may not happen for hours and then occur shortly after cycle-initialization and happen for a minute.
d-Will try the NICAN repair first.  Will also double check the cable terminating resistors and try swapping cards.
e-using ncconfigobjrtsi for object setup for transmit periodic