YM is now in bed with Windows Live Messenger (MSN) and i know msn doesnt work properly if IE7 is not configured correctly. Now if you use Firefox or something else, you still need IE7 for messenger to work.
So set your IE6 or IE7 to this
IE7 (2 minutes)
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Over time IE7 seems to set its own (or programs do) tick boxes in the advance tab.
In IE7 Tools >Internet Options >Advance Tab
Click Restore advance settings defaults button.
Then scroll the listings down to near the bottom and:
1.Tick empty temp files when browser closes (this empties the cache, which if not empty, will stop you from going online).
2.Bullet disable phishing filter (optional. Leave it on if you want that type of protection, usually for financial data like internet banking)
Delete Browser History, cookies, add ons, the whole lot regularly.
Close the browser to set the settings.