Win98 magically kicked off of Win2000 domain controlled network

Sorry to be so long winded below!!
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Our network is on a Win 2000 Server Domain Control.

We have a few Win98 boxes that, from time to time, will be bumped off the
network for no visible or aparent reason.

Once the user tries a "restart" they get the usual "no domain server
available or you've entered an incorrect password". Then we go through the
ritual of trying different combinations of the "Log off..." key, a few more
"restarts", and even a complete shutdown. Sometimes it works, other times it
doesn't.

It was explained to me once that there's some confusion in Win98 between the
"Windows Network Password" and the "Windows Password" that may cause the pc
to lose network connectivity ...

What we've been doing is this, every 90 days Users are prompted to change
their passwords. On the W98 boxes, once the network password is changed, the
"Windows Password" change box pops-up. At this point, we clear both boxes and
hit OK - leaving the .pwl file that's created with no password in it.

Is that the correct thing to do??
If not, what is?

Or is there a fix out there that will make the pc stop prompting to have the
Windows Password changed when the Network Password is changed?

Thanks!
- Kevin