Try the steps listed here:
How do I uninstall or re-install ESET Smart Security/ESET NOD32 Antivirus? (4.0)
KB Solutions I
SOLN2116|Last Revised: May 14, 2009
Due to corrupted installations or newer program releases, reinstalling your ESET security product is sometimes necessary. To uninstall, follow the steps below.
1. Click Start ? All Programs ? ESET ? Uninstall. After you uninstall, you will need to restart your computer.
2. After restarting, click Start ? My Computer. Navigate to and delete the following folders:
Documents and Settings\All Users\Application Data\ESET
Documents and Settings\%USER%\Application Data\ESET
Vista Users must delete the following folders:
To reinstall, first download ESET Smart Security or ESET NOD32 Antivirus onto your Desktop using the links below for Windows NT/2000/XP/2003/Vista.
IMPORTANT: Please check your operating system version before downloading.
ESET Smart Security 4.0: http://download.eset.com/downl...n/ess/ess_nt32_enu.msi
ESET NOD32 Antivirus 4.0: http://download.eset.com/downl...n/eav/eav_nt32_enu.msi
ESET Smart Security 4.0: http://download.eset.com/downl...n/ess/ess_nt64_enu.msi
ESET NOD32 Antivirus 4.0: http://download.eset.com/downl...n/eav/eav_nt64_enu.msi
NOTE: You will need your unique username and password to download your ESET security product. Please reference your confirmation email for this information or click here to retrieve your username and password.
Once the download has completed, you may be prompted to click Run and begin the installation process. Click Run if you are prompted. If not, navigate to your Desktop or wherever you saved the .msi file and double-click it.
NOTE: If the installation gives an error and you previously had ESET Smart Security or ESET NOD32 Antivirus installed on your computer, verify that you have uninstalled it completely according to the instructions above.
Click here for step-by-step instructions with screenshots, or follow the steps below:
1. Click Next.
2. Select I accept the terms in the License Agreement and click Next.
3. Select Typical Installation and click Next.
4. Enter in your username and password that were provided at the time of purchase. (The username starts with 'AV-' or ?EAV-?) Do not select the check box labeled Set update parameters later. Click Next.
5. Continue with the installation by clicking on the Next button. Ensure all ENABLE check boxes are selected.
If you need further assistance with the installation process, please refer to one of the following manuals:
ESET NOD32 Antivirus 4.0: http://www.eset.com/download/EAV4_User_Guide_ENU.pdf
ESET Smart Security 4.0: http://www.eset.com/download/ESS4_User_Guide_ENU.pdf
Also be sure you got the correct language version (English, in your case) as prior
to May 20 only the Czech language update was released
Just a thought .. Are you running Spybot SD or Spyware Blaster ? ?
If so disable them, especially if you use the Tea Timer in Spybot
which will stop certain registry changes from being done while it is on.