AVG detected Trojan Horse SHeur3 and put it in the vault. Am I at risk and what was the aim of the infection?

AVG has done its job so you are safe. Its a very good anti-virus but I have had trojans and virus's whilst using it in the past. I strongly recommend Microsoft security essentials. Its completely free and since using it I have not had any nasty things on my laptop. Its real time too. Just google it and download, remember to uinstall AVG 1st.|||only thing i can suggest is to look it up on google and u will find the answer and the removal tool for the fix