If you have Simple Adblock installed and see the blue icon in the statusbar, then adblocking is enabled.
If the icon is gray, then the adblocker is disabled, and should be enabled by clicking the icon and selecting enable.
If the icon does not appear, please see icon does not appear in statusbar

It the blue icon appears but ads are not blocked, please see the guide below.

Reasons for not blocking ads

Conflict with another Internet Explorer addon
Some addons for Internet Explorer like IE7Pro has been reported to interfere with Simple Adblock. You can verify if another browser addon is conflicting with Simple Adblock by disabling the various addons you have installed, relaunching Internet Explorer and verifying if ads are blocked.

In Internet Explorer goto tools -> manage addons. Here you can try an disable other plugins installed within Internet Explorer. If you find out a conflict is causing the conflict, please reenable the plugins one by one, until you have located the plugin causing the conflict.

Please report back to us if you have confirmed a plugin preventing Simple Adblock for blocking ads, so we can list it on this page.

Issue with Simple Adblock settings
Try and delete all settings files for Simple Adblock.
These are located in a hidden Application Data folder.

Depending on your windows version, it is located in different locations:
XP: C:\Documents and Settings\[User name]\Application Data\Simple Adblock
Vista: C:\Users\[User name]\AppData\LocalLow\Simple Adblock
Windows 7: C:\Users\[User name]\AppData\LocalLow\Simple Adblock

An easy way to access the folder is to type the following path in Explorers address bar:
XP: %appdata%\Simple Adblock
Vista and Windows 7: %appdata%\..\LocalLow\Simple Adblock