Using QlikView 11.2 SR3, attempted connecting to Informix via 64bit 3.x ODBC driver causes QlikView to crash. At other times, once establishing a connection, QlikView would not show any tables to select to load into the script.
Download an older 32bit Informix Driver, 2.90, from IBM.
Here are the links to the driver download page as of October 15th, 2013 (This link defaults to and shows Windows 2000 - select the appropriate download for your needs):
NOTE: You must be registered on the IBM site in order to download the driver. Make sure to Select 'Force 32bit' when selecting tables from Informix with this driver.