Samsung Galaxy S1 Constant Reboot Cycle
Does your sdcard have multiple partitions?

Most recoveries have built-in repair function to scan corruptions in sdcards which prevents your phone from booting properly, it is under Mount -> Repair if you are using CWM.

If it did not help, try removing your sdcard temporarily to check if it boots up properly. If it successfully boots then you need to reformat your sdcard, make sure to backup first.