Help needed in extracting text present between two headers in .txt file

Hi All,
Please help me out in fllowing problem.
I have text file which contains the data in following format.

Contents of file.txt are

setregid02
Test that setregid() fails and sets the proper errno values when a
non-root user attemps to change the real or effective group id to a
value other than the current gid or the current effective gid.
setregid03

Question: I have to find setregid02 string in file.txt and extract
description present between setregid02 and setregid03

Note: 1. setregid02 and setregid03 strings starts after fixed two spaces
and description starts after fixed one TAB(8 spaces) in file.txt in
their respecive lines.
2. I would have only setregid02 string and file.txt are the input to
extract description from file.txt.
3. Next header string(i.e setregid03) can be any string which starts
exactly after two spaces in that line.

As this file contents does't have any delimeters(like :, etc..) I am unable to parse two headers and extract the description in between two headers.
I have tried with few grep, awk and sed options, but couldn't able to find the solution.

Please let me know if any one has solution for above problem.

Regards,
varshit.

pls. Post the i/p , and the output your expecting.

sed -n '/setregid02/,/^  [^ ]*$/{/^  [^ ]*$/!p}' file

cheers,
Devaraj Takhellambam