[strongSwan] ECDSA-384 certificates and Windows 7

[Fred]

Windows username/password dialogue prompt for MSCHAPv2 authentication 
details causes Windows 7 to hang (a crash in svchost) using ECDSA-384 
certificate at strongSwan endpoint. Windows 8 connects just fine.

Is there a way of getting win7 to work so a single stongSwan config can 
be used?

If not is there a way to use RSA certificates for specific users or some 
other selection criteria so win7 and win8 can be simultaneously supported?