I test Trac today.
The version of all components doploy Trac are:
Python: 2.4.4
SVN: 1.4.5 with 1.4.5 py mod for py2.4
Sqlite py mod: 2.3.4 for py 2.4
clearsilver py mod: 0.9.14 for py 2.4
Trac: 0.10.4

What a damn when I install them!
If svn_repository is not set, that means run Trac without SVN, it is fine!
If I set svn_repository path during using trac-admin to create a new project,
python.exe crash! damn!
Ok, then I leave this value to blank, trac-admin run successfully.
After that, I manully set svn_repository path in conf/trac.ini, start tracd, python.exe crash again when IE connect!
Search this in Google, and found a ticket about this:
http://trac.edgewall.org/ticket/1401

From others' comments, I reinstall the SVN 1.4.4 and corresponding 1.4.4 py mod, then everything is fine...

What a sad day....
Hope that the repository created by SVN 1.4.5 before can run peacefully under SVN 1.4.4 now...