For openers boot into safe mode and 'fix' the following problems with hijackthis:

R3 - Default URLSearchHook is missing

O16 - DPF: {072039AB-2117-4ED5-A85F-9B9EB903E021} (NowStarter Control) -

DPF: {7BA7BCE2-D359-4407-82D9-CDF9A74C487A} (DownLoadStub Class) -

Then run another scan and post the results.