virtual raster in QGIS comes from the gdalbuildvrt. You should try to locate gdalbuildvrt on your computer and run it from the command prompt. Size should not be an issue at all because this is what virtual raster files are for. Below is the (simplified) syntax of gdalbuildvrt
gdalbuildvrt [-resolution {highest|lowest|average|user}]
[-te xmin ymin xmax ymax] [-tr xres yres] [-tap]
[-separate] [-b band]*
[-r nearest,bilinear,cubic,cubicspline,lanczos,average,mode}]
output.vrt [gdalfile]*
so the basic command line line will look like this
gdalbuildvrt -overwrite output.vrt input.tif
the -overwrite option delets existing file with the same name as the output.
the easiest way (in my humble opinion) to install gdal is to use OSGEO4W installer. You should the have an osgeo4W shell from where you can launch your commands. Note that this couls also help you update your QGIS and make sure that gdal links are well defined.