Port scanning

I'm using an ageing 3Com ADSL Wireless Firewall Router, 3CRWDR100A-72, XP
SP3.

For about the past week, whenever I use any TCP/UDP application or website,
the router logs are displaying numerous amounts of TCP Fin & Vecna scans,
plus Smurf attacks. I had this problem years ago when I first got the
router, but cured it by creating virtual servers for the apps (or so I
thought).

Whilst checking the latest logs for the router, the page became
unresponsive, the PC blue screened & rebooted, and a few of my files were
deleted.

Last night's log showed both inbound & outbound scans - could the router be
faulty, showing false positives?

Thanks.