Don't remember if there is a SP3 on Win XP. If so, you may need to install that first. The Adobe site has a compatibility guide for AA X (in the store). Also, be sure you are logged in as an administrator and have anti-virus disabled.
Unless you're running the 64-bit version of Windows XP, you'll need SP3 installed. The system requirements for Acrobat X are listed here: http://www.adobe.com/products/acrobatpro/tech-specs.html
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