Originally Posted by scmfxt
I think it's a matter of steps you take from GB to the next rom. For me:
1. GB stock with root.
2. Install sgs kernel flash and flash kernel with CWM (Synthesis).
3. Go into CWM and disable lagfix if it's enabled.
4. Update your flavor rom in recovery mode. NOTE: You will need to flash twice since 1st time give you a warning about partitions.
5. Once flashed it will auto reboot.... HERE you need to remove the battery to power off.. put battery back in and go into recovery mode and flash the rom again since the previous flash only install the new recovery.
6. Install Gapp.
7. CWM: wipe Cache Partition
8. CWM: Advanced > wipe Dalvik Cache
Because I have the Rogers variety, my step 2 uses a different product (the name escapes me but I use ODIN to flash it) and I was able to skip over step 3 (not sure if it was even an option). Overall I had red CWM, but the first time CWM was green (or blue). I think the difference in versions had to do that I installed ROM Manager the first time around and tried to install the i9000 (or something) CWM image. It wasn't successful, but it looks like it made some impact.
Out of curiousity, what colour was your CWM in Gingerbread? Synthesis may be using a newer (more forgiving) version.