Usually this is NOT a HDD or DVD drive issue. This happens as a result of a GPU solder terminal connection fault. This is often a precursor to the infamous "Red Ring of Death" (RROD) error and will most likely require repair. If you're under warranty, send it in immediately, as you want it fixed. If you're under the RROD-only extended warranty, most people suggest you wrap your 360 up in towels and overheat it or do whatever it takes (without voiding warranty of course) to get the console to red ring. After it gets RROD, you can send it in for the extended warranty replacement. Even if it works now, it will most likely go bad again in the near future. You don't want to be stuck with a broken console after your warranty expires (then you'll have to fix it yourself, which can have mixed results, often not entirely fixing it).