Database Import failed (Error Code:IMP-00098)

Hi..,
while importing using the following
imp command am getting the following error, can u please let me know the problem might be what

C:\>imp system/mgr123@db123 file=c:\1\atc_prod_1.dmp,c:\1\atc_prod_2.dmp,c:\1\atc_3.dmp filesize=2000m log=c:\1\atc_prod fromuser=atc_uat touser=atc_dev

imp system/virmgr@arbdb file=c:\1\stc_prod_02-12-2007_1.dmp,c:\1\stc_prod_02-12-2007_2.dmp,c:\1\stc_02-12-2007_3.dmp filesize=200 log=c:\1\stc_prod fromuser=stc_uat touser=stc_80119

Error:
***********
illegal lob length marker 64738
bytesread = 01776219136
TABLE =
IMP-00098: INTERNAL ERROR: impgst2

So, please do the needful.

Thanks in Advance
Giri K.Y.