I was having more troubles with the installation, the file frb3update.tar.gz doesn't disappear from my storage, I have to rename it to frb2update.tar.gz and after that the file disappear.
With the last Kernel-B7610-Froyo-REV87 I have to do the same before, rename all the files to frb2........ and its disappear after reboot. Making all that changes the mobile is working fine.
Can you post the output of dmesg?
howto? well.. Go to dev tools --> terminal emulator
su (then press enter)
dmesg > /storage/dmesg.txt (then press enter)
reboot to windows, you will have a file called dmesg.txt on your my storage. Post it as an attachment here.
Do you use the auto installer?
When you install beta3 with autoinstaller and you apply the update as should be (so, place the zImage, and frb3update.tar.gz on your my storage and start haret) does the frb3update.tar.gz disappear from my storage?