Most homeowners policies will cover the laptop of a friend that gets stolen from your home. The problem that you may run into is that you have to pay a deductible on the claim, and it may not be worth filing a claim to replace the computer. After all, your concerns run deeper than replacing a friend's laptop because you also have to protect your insurance record.
When a friend or relative is visiting you, they are entitled to basic insurance coverages, including their personal property and liability coverage. That way, if something should happen to them or their property, you have insurance to offset the costs and deter possible lawsuits. The question is not whether your insurance will pay for the laptop, but whether it is in your best interests to use it.
When you file a claim for a loss, it gets added to your CLUE report. This report is a comprehensive list of liability and loss claims you have filed across all of your liability policies. The more claims you file, the higher the perceived risk of insuring you. The higher the risk, the more your premiums will be. For this reason, it may be better to replace the laptop out of pocket.
Similarly, your deductible for the claim is likely to be most of the cost of the laptop. If the difference between your deductible and the actual cost is less than, for instance, $200, it makes more sense to go ahead and pay for the remainder out of pocket rather than file an insurance claim. Save your homeowners insurance for situations when you have to have it and you'll pay less for the coverage over the years.