After having formatting my computer (W7-64bits), I have re-installed QGIS 2.0.1-64 bits on it . But I can not use GRASS, SAGA or R via Toolbox (or Processing). I have checked the path in the Options, and I have tried to uninstall and re-install it again, but it doesn’t work yet. In the beginning of the re-install, I have a message telling that I QGIS is already installed, but it didn't remain any folder or files link with Qgis. I checked as well in the option and plugin setting, but everything seem to be fine (plugin activate, plugin repositories connected...).
Did I install something else than QGIS? did I miss a step, etc.?
Many thanks for help!