I remember I also had such problems with the equipment for the concert. Of course, at first, I tried to fix everything myself. But all that I did was clearing the cache, but it didn't help. Sound and light equipment I hire at this company.
truesoundhire.co.uk It was luck that they have excellent customer service and they helped me to fix everything very quick. They came to the venue and sorted it out free of charge. Their engineers and staff are experienced, trained and passionate about what they do. I was very pleased of their quality of work, so, I have already hired the sound and light equipment from them three times.