FileStore: exception thrown when more than one : is used in SessionID

When only the SenderSubId or TargetSubId contain a : the engine starts fine. However, when both SendSubId and TargetSubId contain colons : an exception is thrown and teh engine does not start.

For example:
SenderSubID=ABC:ABC
TargetSubID=TEST

OR

SenderSubID=ABC
TargetSubID=TEST:TEST

start fine but the following fails with (The filename, directory name, or volume label syntax is incorrect):

SenderSubID=ABC:ABC
TargetSubID=TEST:TEST

It looks like a windows problem with the : in the file names but I was hoping that something could be done to the engine to replace the : internally or another work around. Unfortunately, exchanges like the CBOE require colons in both those fields.