Still dogged by problems in its real estate portfolio, CalPERS and its partners are facing legal action over $260 million worth of office deals. CalPERS and CommonWealth Partners were sued last week for missing a mortgage payment on an office tower in downtown Portland, Ore., the Oregonian newspaper reported. CalPERS and CommonWealth, a Los Angeles real estate investment firm, bought the building for a reported $108 million in June 2007. Earlier this month, CalPERS and Hines, a Houston real estate firm, were hit with a notice of default on a $152 million mortgage on three office buildings in Emeryville, according to Alameda County records. The two cases provide fresh evidence that the troubles in the real estate market have spread from housing to commercial.