This is quite an old thread
Several threads were already created here related to the said problem, say :https://forums.comodo.com/verification-engine-cve/verification-engine-please-help-resolve-some-contradictions-t71775.0.html;msg510872#msg510872
Interesting thing is that 3rd party uninstaller (I tried Revo) may not help. See the subsequent link:https://forums.comodo.com/general-discussion-off-topic-anything-and-everything/troubles-with-ie9-upgrade-vengine-t71617.0.html;msg509696#msg509696
What I meant - it may happen – just manual uninstall (removing folders and Registry leftovers) may work , but if Iobit Uninstaller suggested will do the job – fine, despite my doubt(s)
Anyway since the initial poster did not reply since I hope he/she read all the above and solved the problem
Had to use command line to delete the folder and DLL file before I could open control panel to uninstall.
, which is reflecting part of what I was writing in the referred thread about uninstaller's failure and manual cleaning procedure