I have read quite a few reports of 'SH3_XPSP2_Res_Fix_for_1.4b' either not working properly, or resetting itself.
The link I have posted has never failed to work for me.
It consists of 2 files.
A dll and a cfg.
Just drop them both in your SH3 folder, edit the cfg with a text editor to set the resolution you want, and you're good to go.
No bat files required