Have the firewall on a nightly reboot. Unless you're using a Sonicwall or other pro FIrewall/router you need to have them autorestart at least every couple of days for optimal performance.
Cisco ASA, so that is probably not it. Uptime isn't a problem for the ASA-- sometimes I wish it would die so I could replace it with something more friendly, but it just keeps on going!
Yeah that should be ok. Although I've seen SPI on those cause issues.