It could be your pre install wipe and format procedure needs looking into or your downloads are getting corrupted.
Look here: Do not Factory Reset your Rooted Phone
start at step 8
To check the MD5 sum (this verifies weather your download is clean or corrupt) use " MD5 Check Utility" . I think it can be found at CNET downloads. It comes with a read me txt.
The most stable ROMs for the V are in fact Gingerbread ROMs based off the IHO repository.
The best are the Harmonia2; MiRaGe; and the 01312012 build of the BACKside ROM. Each one comes with an MD5 sum that you need to copy if your going to download it. Use it with the Utility once downloaded onto computer.
Look in the All Things Root Guide sticky for more info on the first two. The last one I can link you to if you want to try it.
These a extremely stable ROMs when everything that's required to wipe and format has been acomplished prior to flashing. Don't forget to install the Gapps after the ROM. If you want to flash a theme, wait until after you have rebooted the new ROM at least twice.
Hope this helps you get a ROM on your phone you can truly enjoy.
Note: When overclocking only use the menu/settings/CyanogenMod settings/performance/ CPU. When overclocking the min should be set to 480MHz and left there. Set the Max at 748MHz and then open up the Gallery and try some options. Do this for each setting above 748MHz until the phone auto reboots or the Gallery freezes. Then drop setting down 2 settings. This is where you can be safely overclocked to.
Make sure you don't check the "set on boot" option until after you have found the safe overclocking setting.