Exchange Recovery Problem

[gdc2001]

When we try and perform an Exchange Recover we get the following message:

Started PerfMon update thread (Id: 285)
Performance monitor update thread running
Recovering Microsoft Exchange Information Store ...
Too many Exchange Server filenames in NSR Index -- Invalid index.
rcmain.c(857): process_is_recover() = 0x00000585
Processed 0 files 0 KB in 0:01:21 0 bytes/second
rcmain.c(868): end_is_recover() = 0x00000585
Completion time Tue Nov 13 09:37:14 2001

Is it an index problem or somthing else.