ppp-conection now ceases soon after request was sent to a server after kernel update

[s-strong]

I've upgraded my default FC5-kernel to the lates one and found that ppp-conection now ceases soon after request was sent to a server. Say, it downloads some kb from server and halts (no packages are going). When I returned to the default one it works again. It works even when both kernels are present, but if the default one is removed - the probplem repeats. What can I do to fix it?