The reindex command line utility can be used to fix a corrupted appdix.mdx, but it changes the displayed order of a second field, when multiple records with the same policy number are displayed.
1. Respectively rename appidx.dbf, appidx.mdx to appidx1.dbf, appidx1.mdx
2. Create a dummy fsisys.ini
3. Execute "db2dbw32.exe /I=fsisys.ini /ST=appidx1 /SD=appidx.dfd /TT=appidx /TD=appidx"