Hello,
Not a solaris or Linux guy myself the index process should not be much 
diff then windows.
1. recreate the index from stratch , remove any index entries of the 
problem client first, this can be done by nsrck cmd.
2. Run backups and confirm if corruption still exists.
3. Update client on problem machine, repeat step 2.
4. If problem still exists, then check and make sure, server has enough 
diskspace, index path for client etc are good, i have seen a duplicate 
index path in certain circumstances, usually, a file or two exists in 
debug directory also, tip off that something is worng, deleate all tmp 
folder files, rerun backups and confirm.
5. Also run nsrim -X it may be that media index is having some issues.
6. Check compatibility etc for the client\server and double check client 
configuration.
HTH

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