This worked 100% for me. Uninstall download accelerator plus and select "Custom Uninstall". Choose "select All" for every page. finish the uninstall and THAT'S IT! Everything went back to normal. P.S. Internet Explorer, Chrome, and firefox were effected and are fixed by this.
Like you, I put a lot of money into my PC and a hijack by any program in UNACCEPTABLE, I felt your pain.