Yes, you can reinstall an earlier version of Chimera.  Multiple versions can be on your computer at the same time.  But first, try running Chimera's Tools / Utilities / Browser Configuration tool to reassociate .pdb files with chimera.  And as you know, you can always use Chimera's Open dialog.

    HTH,

    Greg

On 06/02/2014 11:17 PM, Robin Parmar wrote:
Hello,
Warm Greetings!
Thank you for Allowing me to use Chimera through academic license.
Yesterday(June 2nd) I was prompted to update Chimera to 1.9 version.
I accepted and installed it successfully on my system (windows7pro). Before that I had removed Chimera 1.8.8.
The problem I face is, I can not open certain .pdb/.pdbqt fies saved in my comuter. such files even do not exhibit chimera logo which earlier version did. Even with "choose default program"  system can not open these files insted other program (like spdbv) open them.
I have not made any change in my system after installing new version.
 Can I reinstall earlier vrsion(1.8)?
Kindly suggest me what best I should do to avail service (Academic Research) of chimera again.
 Regards. 

-Robin