Ah, the confusing world of OS/2... I'll touch on the relevant things...
Re: the swap file.
I believe I am remembering this correctly. The absolute maximum the swap file can be, on ANY iteration of Warp/eCS, is 2GB. Even a byte longer will cause a crash (probably a trap 000e, if my memory of what such an attempt calls).
If for some reason, with a swap file set at 2GB, something tries growing the file, regardless of it being on a JFS partition, this will occur.
Also, if memory serves, the reason for this (unless something has changed very recently) is that the code that handles the swapper.dat file is not capable of handling larger than 2GB files, regardless of underlying file system.
I will be making adjustments to the SWAPPER.DAT file to reduce the minimum size to 32 MB or even 16 MB at startup. I will also have to make adjustments to the VIRTUALADDRESSLIMIT to make it less than 2 GB or that the OS/2 VM will be more stable.
Sadly, I don't know the mechanism that handles all swap file access. This will hopefully help.
I have allocated 640 MB of memory with the latest internal revision of OS/2 Warp 4 and ironically, it works. I recall that the original release of OS/2 Warp 4 (and FixPack 15) was not designed to handle more than 512 MB of memory as it will lead either to system instability or even "A unrecoverable processor error has been encountered". I might have to reduce it to 512 MB just to be safe.
That was actually never the case. But, for most people, it was close enough that people thought it was. Certain hardware never had problems with larger memory amounts (notably numerous IBM workstations and servers in the Intellistation and Netfinity line respectively). Thus, I guess for most people, it's an applicable problem, but not for the reasons they think.
With the current kernel you are running, and assuming you have updated the other files that should have been updated with it, like OS2LDR as one example, you should be able to use a full 4GB (minus address space used for bus resources).
As for the IBM1S506.ADD driver, I found that with FP15 and the updates applied, it is capable of supporting hard disks larger than 8,032 MB (7.84 GB) and up to 64 GB per HPFS partition (on hard disks larger than 64 GB). I used the updated installation floppies for hard disks greater than 8.4 GB to install OS/2 Warp 4, btw.
The 8GB limitation doesn't exist in Warp 4. FP15 (with LVM) extended partition size support, but to a far higher number. The 64GB limitation, btw, is solely for HPFS drives, thus using JFS alleviates that.
The 8GB limitation (or 1GB, or 2GB or 4GB, depending on card) STILL exists for various SCSI cards. That is due to those cards being limited by it's BIOS' boot capabilities.
Once that is finished, I will be installing Firefox 4.0.1 under a temporary directory C:\FF.401 to see if the right click crash goes away.
If it does or if it still doesn't, I'll let you know.


Good luck!