create index stalls entire informix server

Hi, I'm creating a detached index on a very large table (nearly 200,000,000 rows). When I run create unique index w_freqNum on w_standard(Identifier,Year,tsFrequency,tsNumber,FieldNumber,NoteLink,RecordSequence) in w_stnd_index1; the entire server stalls for the other user of the system. My colleague's select query references a table in another database and the table is in an entirely different dbspace as my table and index. When I hit ctrl-C and execution stops, his query of the database completes immediately. I am using Informix Server 9.30 running on Solaris 8, Sun E3000 system. Any idea why this happens, and is there any way to allow both to run simultaneously? Thanks, Steve