Thanks to Jon Freeman at Mudcat for encouragement and help. If you've read the previous posting on this you'll know all about my unending problems with realplayer. Last year I had none, so these comments relate only to versions later that '98.
Thanks to Real Support for their help, incidentally I also updated my soundcard drivers - this redirected errors from VMM faults to GDI faults. Made trouble shooting pointers much more useful.

1
The install of G2 hangs    '.r32_g20_3sm.exe' Invalid Page Faults etc.'
Fix A
Real recommend a complete uninstall of previous versions and reinstall of G 2 or V 5 depending on the error message you receive. Please go to the Real knowledge base at these links are read em.
Ill operations page faults etc.,
RealPlayer Knowledge Base  Please enter 'illegal' in the search box then go, next 'invalid page fault'.
Do exactly as they instruct - a basic Windows uninstall will not be enough, also do check the permissions; on the 'tem', 'temp' and 'system' folders on your computer. No 'read only' box should be checked.
*A*N*D*   B
Remove unnecessary stuff from the systray
Explanation.
Frees up more memory. I could not remove systray itself but I did take the Volume control out by unchecking 'Run in System Tray' box on the Multimedia property page in the Control panel.
2
realplay.exe  has caused an Invalid Page Fault and/or has Performed an Illegal Error etc. other examples in this category are 'gdi.exe' lock ups.
Fix
Set the Video Adapter to default settings especially the Refresh Rate - right click on any blank part of the Desktop - select 'Properties', 'Settings', 'Advanced Properties'
Explanation.
Video managed by Windows seems to get thrown any old where in memory so that realplay.exe may assume that a range is free - video card default ranges are know to realplayer/ DLL - and a write is performed- but Windows already has grabbed that range for Video under an Optimization routine?
3
PNEN???.DLL has  caused an Invalid Page Fault.
Real tech support are working on this one but I believe I have narrowed it down, at least on this
Intel Triton type motherboard. Windows manages data coming form the modem but that can be prevented by installing a 3rd party utility for example from the maker of your modem. In my case it is a Usr modem so it's Usr Modem Manager.
Fix.
Disable Windows Modem management by installing your modem's own utility.

Notes
The data comes from Mudcat to your Modem which passes the data to Windows 'messaging services' then it is sent to the sound card - however since there is also activity on your screen, video requests/routines have to be accommodated. Please note that the largest chunk of memory here is video - in effect getting more video memory can prevent a lot of these lockups. Problems seem to be happening when realplay.exe assumes stuff about where things are in memory especially video images and updates etc., so it is possible to lock up yet still hear audio for a considerable time.

Page faults as you already probably guessed are memory problems, the PC 'pages' memory, i.e. writes and reads stuff by chunks called pages.... :0)
Illegals are CPU and/or File permission problems - i.e. certain levels in the processor are out of bounds to certain file/routines - and some files cannot be overwritten or altered so they are set to read only by an attribute command. During a crash code is messed up in memory and the result can be a garbled command which is illegal. When that code gets accidentally written to disk then you've really got a problem. Examples 'non system disk' etc.