It may be a problem with the update which System Restore can reverse, however it sounds like infection from a renegade search (spyware) provider, or corruption which has built up from the bloated factory preinstall.
Check for infection by installing, updating and running Malwarebytes full scan,
if necessary from Safe Mode.
Then run SuperAntiSpyware full scan.
Make sure you have the Windows 7 Firewall turned on and are using a good AV like free Microsoft Security Essentials
or Avast6. Run a full scan with either of those.
Next follow these steps to clean up a bloated factory preinstalled computer, particularly achieving a clean boot where only the OS and your AV start with Windows. Clean up factory bloatware
In addition after unchecking everything in msconfig>Startup besides AV, enter msconfig>Services, select "Hide all MS Services" then uncheck everything still running except AV. Check back periodically with both lists to make sure nothing has snuck back in - if so turn it off in its program Preferences or uninstall it.