We understand that you are having difficulty running HijackThis. However, in order for us to help you it is necessary that you provide us with a HijackThis log. For Windows Vista, try right clicking on the HijackThis icon and select "Run as Administrator." If you are still unable to run HijackThis, it may be due to malware. If that's the case, it is possible you may be able to trick the malware into letting you run HijackThis.
First, download HijackThis to a clean computer, then rename it from HijackThis.exe to any other name you want, using an .exe extension, for example... YourLastName.exe. Once you have done that, burn it to a CD (preferable to using a flash drive that may easily become infected) then transfer the renamed file to the infected computer and run a scan, then start a new topic and include your HijackThis log.
Please follow the guideline at the link below to start your new topic and post your HijackThis log. If you are unable to create and post a HijackThis log, then your only option may be to reformat your computer and reinstall the operating system. This topic is now closed. Please start a new topic by following the HijackThis Guideline posted here, just be certain to rename HijackThis if it appears that malware is preventing you from running the program: >Guideline for posting your HijackThis log<