maestrowork said:
Microwave is one word. So it would be "microwaving." Unfortunately, it's a noun used as a verb much like "xerox." We'll just have to get used to this usage.
Like hammering, cementing, bicycling, golfing, and countless others.
Xerox is a trademark, and should be capitalized as such. That is a different issue from making a verb form of a noun. Related is the use of a trademark to denote a type of product (Xerox for any photocopy, Kleenex for any facial tissue, and so on). It may be best to avoid using brand names as though they were generics, although dialogue can present some problems there, as people do often use brand names to represent a type of product. The average person will not say, "Hand me a Kleenex brand facial tissue, will you?" Or, "I'll go across the hall to photocopy this article for you." Many (most?) would use "xerox" as a generic term AND a verb, not even mentally capitalizing it.
Trademarks must be protected or they are lost, so companies with valuable trademarks protect them. That is, for example, why you will see advertisements in writers' magazines pointing out that Caterpillar is a registered trademark, to be used ONLY for that brand of equipment.
--Ken