Toad Error : Access violation at address 00000000. Read of address 00000000

If you have two 10g clients installed only the first one listed in the
environment variable path works in Toad 9.5.  The other gets an access
violation error.  Could you please try and switch them just to confirm
that is the same with yours?

  For Example:

1.         Right Click My Computer

2.         Properties | Advanced tab

3.         Environment Variables

4.         Scroll down system variables to Path | Edit  

Path=Developer-Suite 10 GR2 ; Oracle Client 10.2.0.1.0;

  to


Path=Oracle Client 10.2.0.1.0 ; Developer-Suite 10 GR2;