Multiple IPSEC clients/vendors on one winxp PC

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We have to install various IPSEC clients on our XPPro PCs to support various
customers, but when we install a second IPSEC client from a different vendor
(e.g. CISCO and Nortel) we have all kinds of problems with network
functionality - mainly they stop working on that PC. I though I read some
time ago that XP can only have one IPSEC client resident at any given time.
Anyone with more info on this matter or how to have 2 IPSEC clients working
on the same PC would be a great help.

TIA
.