Insufficient memory, md5 combo

[lowly]

Hello there, i have researched on the whole forum and wiki for this error, but i couldn't find something usefull for my problem.
I have a combo user:md5, and i use this command

Code:

hashcat64.exe -m 0 -o C:\hashcat-3.00\hashcat-3.00\cracked.txt --remove C:\hashcat-3.00\hashcat-3.00\hash.txt --username --outfile-format=2 C:\hashcat-3.00\hashcat-3.00\wordlists

I want the output to look like user:pass but, after a few seconds i get this error

I have 8 gb ram, could run only with hashes, but with combo doesn't work...... Help please, thanks