WampServer 2.5 – 32 and 64 bits

Be sure that you have installed Visual C++ Redistributable for Visual Studio 2012 : VC11 vcredist_x64/86.exe
http://www.microsoft.com/en-us/download/details.aspx?id=30679

Don’t Use previous WampServer Extensions/Addons. 
There are no more compatible with the new wampserver version’s (VC11)

Apache     : 2.4.9
MySQL      : 5.6.17
PHP        : 5.5.12
PHPMyAdmin : 4.1.14
SqlBuddy   : 1.3.3
XDebug     : 2.2.5

Source: readme.txt, updated 2014-05-01