The MySQL DLL (libmysql) can't be loaded on WinXP Pro x64 with MySQL 5.0.37 64Bit version.
This may be more of an Regina problem but you should know about it.
Failed to load external library "libmysql": LoadLibrary() failed
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I don't have access to Windows 64bit, but it may simply be a case of Regina being a 32bit application cannot load 64bit DLLs.