* Company says PCs vulnerable to attack by malicious sites

* Microsoft says free security tool can protect against attacks

* Warning affects hundreds of millions of Internet Explorer users

* Security experts say it may be easier to use another browser

By Jim Finkle

BOSTON, Sept 17 (Reuters) - Microsoft Corp warned a newly discovered bug in its Internet Explorer web browser makes PCs vulnerable to attack by hackers and urged customers to download a piece of security software to mitigate the risk of infection.

The security flaw affects hundreds of millions of Internet Explorer browser users. Microsoft said attackers can exploit the bug to infect the PC of somebody who visits a malicious website and then take control of the victim's computer.

The software maker advised customers on its website late on Monday to install the security software as an interim measure, buying it time to fix the bug and release a new, more secure version of Internet Explorer. The company did not say how long that will take, but several security researchers said they expect the update within a week.

The free security tool, which is known as the Enhanced Mitigation Experience Toolkit, or EMET, is available through an advisory on Microsoft's website:

The EMET software must be downloaded, installed and then manually configured to protect computers from the newly discovered threat, according to the posting from Microsoft. The company also advised customers to adjust several Windows security settings to thwart potential attackers, but cautioned that doing so might impact the PC's usability.

Some security experts said it would be too cumbersome for many PC users to implement the measures suggested by Microsoft. Instead they advised Windows users to temporarily switch from Internet Explorer to rival browsers such as Google Inc's Chrome, Mozilla's Firefox or Opera Software ASA's Opera .













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  • Spot Watch

    Launched in 2004, the Smart Personal Objects Technology (SPOT) watches connected to Microsoft's FM radio-based network (MSN Direct) and delivered weather reports, news snippets, stocks and sports scores to users. <a href="http://news.cnet.com/8301-17938_105-9927213-1.html" target="_hplink">Writes</a> CNET, "Microsoft put a lot of money behind the Smart Watch and partnered up with Fossil, Suunto, Swatch, and even Tissot, which produced a high-end, touch-screen model that cost $800." Critics and consumers were not buying it, though. <em>Washington Post</em> reviewer Rob Pegoraro tested a $300 Suunto model and <a href="http://voices.washingtonpost.com/fasterforward/2008/04/microsofts_spot_watch_winds_do.html" target="_hplink">wrote</a> the following: "[It was] too big, too ugly, too useless, too expensive (especially with a $9.95/month subscription charge for Microsoft's MSN Direct data service)." The devices were discontinued in 2008.

  • Courier Tablet

    The <a href="http://www.huffingtonpost.com/2010/04/29/microsoft-courier-cancele_n_557493.html" target="_hplink">Courier Tablet</a>, leaked in 2009, was expected to be announced shortly before the iPad's debut in January 2010. According to rumors, the device would have featured two seven-inch screens that folded shut. However, this innovative twist on the tablet PC never saw the light of day. Microsoft instead unveiled a comparatively "<a href="http://www.huffingtonpost.com/2010/01/07/hp-slate-tablet-microsoft_n_414364.html" target="_hplink">underwhelming</a>" single-panel tablet device called the <a href="http://www.huffingtonpost.com/2010/01/07/hp-slate-tablet-microsoft_n_414364.html" target="_hplink">HP Slate</a>, which PCWorld called "<a href="http://www.pcworld.com/businesscenter/article/186247/hp_slate_lowers_the_bar_for_apples_tablet_pc.html#tk.mod_rel" target="_hplink">a mediocre device</a>" and "<a href="http://www.pcworld.com/article/186172/why_the_microsofthp_tablet_is_a_big_disappointment.html" target="_hplink">a big disappointment</a>." By late April, both the Courier Tablet project and the HP Slate were tabled. <blockquote><strong>UPDATE:</strong> A post written for the official Microsoft Blog in 2010 clarified that the Courier "project" was <a href="http://blogs.technet.com/b/microsoft_blog/archive/2010/04/29/speculation-about-the-courier-project.aspx" target="_hplink">never an official Microsoft product</a>. The statement read: "<em>At any given time, across any of our business groups, there are new ideas being investigated, tested, and incubated. It's in Microsoft's DNA to continually develop and incubate new technologies to foster productivity and creativity. The 'Courier' project is an example of this type of effort and its technologies will be evaluated for use in future Microsoft offerings</em>." The HP Slate was the result of a partnership between Microsoft and Hewett-Packard.</blockquote>

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  • The Zune

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