I had a similar problem a while back. Turned out the text size on my browser was set too large. You didn't say what browser you use so I'll assume it's Internet Explorer. On the toolbar at the top click view and then text size. Make sure "normal" is selected. That cured my problem. Hope it helps yours.
On some websites such as google, the font is abnormally enlarged and the spacing between sentences is huge. On other websites the spacing is normal. This issue began two days ago after I downloaded a bittorrent video file. I have tried to erase the bittorrent program and files. Also, I have run the free versions of adaware, spydoctor and kaspersky antivirus (kaspersky noted a trojan) though I rebooted and the issue persists. I have windows xp-service pack 2 has been installed. Any ideas on a resolution? Thank you.