Actually we are not seeing any issues as far as 4.15 and xp, all of our users that are using earthlink and verizon, we have them install 4.15 because 4.6 is not compatible with WinPoet (a pppoe connection manager) and if 4.6 and winpoet is installed, well say bye bye to your pc untill you clean off any trace of winpoet and nortel.
As far as the fix about the registry, awsome! that one had me stumped for a bit, but now that I know where the second half is located, it is easy as pie now. Here is to further explain the fix (or add onto it):
There is two keys involved here: the first key is located at:
HKEY_LOCAL_MACHINE - System - CurrentControlSet - Class - {4D36E972-E325-11CE-BFC1-08002BE10318} - 0001 to 0014 depending on your configuration. Check this key first, click in each of the 0001, 0002....0014, and look for the key that lists the "Nortel IPSECSHM Adaptor" under DriveDesc in the preview pane, now write down what folder this is, I have seen it under 0006, 0007, 0008, 0014.
Now go to the other key:
HKEY_LOCAL_MACHINE - System - CurrentControlSet - ENUM - ROOT - NT_IPSECSHM
now when you enter the key as stated by zarafu,
"Highlight the "Driver : REG_SZ : " in the right pane, choose EDIT - STRING from the menu. Enter the value: {4D36E972-E325-11CE-BFC1-08002BE10318}\0008 in the field for "value". Click OK to proceed." where 0008 is listed, make sure that you list the folder in which you found the ipsecshm in.
Again thanks Zarafu for the fix, I have searched for a week on this, I have tested it on several machines now and the fix works wonderfully.