It appears that the official Shareaza website has been hijacked by some scammers, who are promoting some sharing software which is filled to the brim with adware and spyware. Such scams are common but rarely do they take over official sites, and this could well cause some confusion for a long period.

For your reference, the way to get Shareaza now is via their SourceForge page here.

If you have downloaded from the malware infested site, please use some adware removal tools ASAP!