For your future reference:
If you press and hold Shift as soon as IFX starts running, it will display a recovery screen. Your options are to continue (which aborts IFX) or to restore any of the last 3 good copies of os2.ini and os2sys.ini that IFX has saved. (Note: you can probably press and hold Shift at any time after JFS chkdsk runs to get the recovery screen - you don't have to wait until the last second).
For your current problem:
After you've booted successfully, please go to x:\sys\apps\ifx. You'll find 4 log files there (ifx.log, ifx1.log, ifx2.log, and ifx3.log). Please zip them and either send them to me or post them here. One of them should identify where the hang occurred (provided you haven't rebooted more than 3 times since then).