A Twitter user's complaint last week in which he produces photo evidence of HP warning him that his ink cartridges would be disabled until he starts paying for HP Instant Ink monthly subscription service has gone viral on the social media.Ryan Sullivan, the user who made the complaint, said he only discovered the warning after cancelling a random HP subscription -- which charged him $4.99 a month -- after "over a year" of the billing cycle. "Cartridge cannot be used until printer is enrolled in HP Instant Ink," Sullivan was informed by an error message.