Some questions

[FLG]

No you can't repair a bridge for railway units. By bridging you are putting up a temporary structure for road traffic, not rebuilding the whole railway bridge.

If you are playing your campaign PBEM check in the options menu as to whether "PBEM No File Save" is ticked. If it is you can't save.

There is a bug here as well. If you start a campaign with "PBEM No File Save" off you must ensure you never run a turn with it on. Normally altering such options don't modify existing PBEM settings, but not in this case. And once "PBEM No File Save" has been turned on you can't turn it off again.

So be careful using that setting for starting other PBEM games. Best to keep it turned off and only turn it one when you need it.

As to Norton, I can't help. Though I would say it isn't a great anti-virus product.