looks like my wireless router has been exploited. Any Ideas?

Model: Linksys wrt54g
Firmware: DD-WRT v23 SP2 (09/10/06) micro

For a while now I've noticed my wireless connection disconnecting at
odd times. Recently connected to the wireless router and saw that
limited or no connectivity message. I was unable to get rid of it
short of a hard reset to the router. After setting the router up
again I made a backup of the configuration. The firewall on the router
is set up so it was surprising to see attempts from the outside to
connect to my computer. After noticing that the firewall was not
working I backed up the current settings to compare with the earlier
settings. It looks like something new has been added to the
configuration. Something called Ort has been added with a strange
ASCII character that means End Of Transmission. Does anybody know
what to make of this.