eMac 1.25Ghz Combo Drive CD Burning Troubles


My eMac is about six months old (1.25Ghz,Combo Drive,512MB) but until last week I had no troubles with it. The eMac will play any CD-R or DVD but it will not burn any kind of CD-R or CD-RW Disc. I tried Sony CDRs, TDK CDRs and Staples brand CDRWs. Every try ended with an Error message saying: The disc could not be verified and it can not be used anymore. Interestingly, my Dell P4 computer at work (with CDRW drive) does not have any problem with the same Blank CD-Rs or CD-RWs. I tried Apple Hardware Test bunch of times and it doesn't find any problems. Does anyone have an idea??