As I said a very occasional one of either T3 or T4 timeouts are fine. A number of them consecutively indicates a loss of communication to the cable operator and will cause the modem to go offline.
Please note your one occurance and the 19 occurances in one go in the screenshot above yours, which is sufficient to disconnect a modem.
http://www.dslreports.com/faq/powerl...Questions#8560 is a nice, quick and
accurate bit of information on timeouts, the links it provides are good for the hardcore cable geeks
DHCP warnings are nothing to write home about.