PCI-24781 in Combination With Doxorubicin to Treat Sarcoma

* In the phase I portion of the study, since we are looking for the highest dose of PCI-24781 that can be administered safely without severe or unmanageable side effects in participants that have advanced sarcoma, not everyone who participates in this research study will receive the same dose of PCI-24871. * Each treatment cycle is 3 weeks (21 days). Participants will take capsules of PCI-24871 for five consecutive days starting on Day 1 of each 3 week cycle. On Day 4 of each cycle, participants will come to the clinic to receive doxorubicin intravenously. * At specific time intervals, participants will return to the clinic for the following tests and procedures: physical examination, vital signs, blood tests, urine test, EKG, assessment of the tumor by CT scan, and an ECHO or MUGA. * Participants may remain on the study for a maximum of 6 cycles (about 4-5 months). After the last cycle, as long as the participant is showing benefit, they may elect to continue taking PCI-24781 alone, in which case they will continue in this research study until there is evidence of their tumor growing.