mac newbie: broken internet connection!!

hi Folks,

I've been migrating from PC to mac for the last while, but this one has got
me baffled.

my mac (powerbook G4) has been doing some weird things lately, like losing
all my email passwords, losing date & time settings, losing memorized
passwords to email acc'ts etc.

anyway, i turned it on yesterday, and i got two strange "firewall" warnings
(never knew the mac had one built in) (os X 10.5.8) ... informing me that
two local proccesses wanted to accept connections from the internet and
would I allow. I said "no" to both, because neither was an app that I
recognized. (one was some kind of 5-letter process whose name I promptly
forgot...)

anyway - since denying them, my browsers cannot connect to the net, even
tho' my wireless signal is connected and strong. when I go into the system
firewall, I can't see that "5-letter thing" on the list of services and apps
anywhere.

I'm fairly up on PC firewall stuff, so if anyone can translate my mac woes
into PC terms, or offer any advice, i would much appreciate...

thx ...