I see you have old video card with bad support of OpenGL, and I have some computer with similar video card (ATI Radeon 9600 with 128 MB Ram) which a true shit, but it gives me ability to debug PGE Engine (which currently supports OpenGL >=3, therefore I planned to make backup SDL-based software render to allow play episodes via it). PGE is a toolset with engine and editor, not editor-only, but it's editor only temporary because engine part is still in alpha-state.
Also, my suggestions:
1) install Windows XP into separated partition and boot into it each time when you wish play SMBX.
2) You can try to close EVERYTHIN: Firefox/Chrome, Skype, Other messangers, etc. to have CLEAR DESKTOP (with no junk software running), and also set turning off Aero while you trying to run SMBX, this would speed-up SMBX working
Also, a small hint if you still choice to sit on SMBX 1.2:
PGE Editor is supports resaving into older SMBX formats: you can use it to convert levels made on modern SMBX'es into legacy format to take ability open those files in SMBX 1.2.2 and older [PGE supports saving even for SMBX 1.0!!!], but be sure than you will lose some parameters which are working with modern SMBXes:
1) open any level/world map in the PGE Editor
2) click "Save as"
3) Choice in the "File format" combobox the "SMBX 1...64" and press OK
4) In the spawned dialog type the "58" numver (Which an SMBX 1.2.2) or "59" (SMBX 1.2.2 Beta build 59)
List of SMBX Version codes:
SMBX 1.0.0 - 1 or 0 [intro.dat it's a level file in format 0]
SMBX 1.0.2 - 2
SMBX 1.1.1 - 18
SMBX 1.1.2 - 20
SMBX 1.2.0 - 28
SMBX 1.2.1 - 51
SMBX 1.2.2 - 58 and 59 for a newer Beta
SMBX 1.3 - 64
Note: you can save file into any not listed version codes, so, listed version numbers are maximum to take ability open level file correctly in that SMBX version
Note 2: look this specification to learn WHAT level file will lose when you will save it into older file format (light-green tags with greater/lesser signs are hints which minimal version supports that parameter in the file):
https://github.com/Wohlhabend-Networks/ ... iption.pdf
P.S. Windows 8.1 machine I have at job