I maybe dns hijacked by isp

I just changed my computer mac address with mac makeup..the isp blocked us to use the router and we are forced to use one adsl dial software offered by it which is baggy and full of ads.I am freaked out with the annoying dns hijack.The network connection was blink out for a while after I changed mac address.It seems that there is no need to restart the computer to let the new mac work..Oh,it is unlucky that I am hijacked even by changing my mac address.I tried another method by installing a software called Share Shield.It seems that it works now,though I still has very slow connection to some sites...I encountered another problem:I cannot drag and drop files from my desktop to trash bin,very strange,I do not why?