Follow instructions by Id242 and Gizmo:
Delete all files under /templates/compile but index
Check permissions on folders, both /templates and /templates/compile are 777
went to Tools & Information-->Permission Checks and got green "OK" on all lines
Test again all 3 directories and got the same issue, all responded with browser error:
Fatal error: Call to undefined function smartyPrepare() in /home/imigcom/public_html/forum/libs/html.inc.php on line 692
Let me know what else can I do to test it.
Tks.