could be. If you reduced your TC to get running slowly increase it. Most find they are getting around 50% normal scrypt hashrate.

Yeah, I agree with Aleks, you should get maybe 350kh/s, but only when comparing the same intensities. If you can get TC higher do that first, then once you've found the highest TC you can reliably start at, start increasing memclock and cpu clock, once you've maxed them out, then tweak the intensity up. About 12 should be find for desktop use, and for a mining rig that isn't used for anything else you'll get to I18 or I20 before it becomes unstable.

You need to use a lower thread-concurrency than usual, maybe 75% of what you normally use. You can also expect about 50% of your normal hashrate due to the different algorythm in vertcoin.

Post your current settings (or command line switches) and we'll try to help.