The version of usrlibt.dll included with 4.521/4.617 prevented the win1632w.exe program (used to allow 16 bit programs to work with 32 bit DP4) from working.
Where the version affected is given as 4.5xx or 4.6xx, all versions of DP4 issued prior to the date of the fix are potentially affected. Where a specific version number is given the problem was introduced by that release and prior releases are unaffected. If a patch release number is also specified (in parentheses) , the fault was introduced at that specific patch level.
Due to limitations on available web space downloadable fixes are only available for the most commonly used environments, and may not be separately available in both 4.5xx and 4.6xx flavours. If a file you require is not available you can ask us to e-mail it to you.