Updated from 11:22 a.m. Some users of Google's ( GOOG) online payment processing system Google Checkout are experiencing technical glitches. The service, which some analysts say poses a competitive threat to eBay's ( EBAY) PayPal, sometimes takes longer than anticipated to process orders. The delays are caused by Google Checkout's fraud protection features. "Occasionally, these procedures result in brief delays for a small percentage of users," the Mountain View, Calif.-based company says in a statement. "We are continually working to make the process as efficient as possible to ensure that Google Checkout is secure and convenient for both merchants and buyers." In addition, some shoppers have complained that orders through Google Checkout have been canceled without justification, according to IDG News Service, a trade publication that earlier reported the glitches. Customers have complained to merchants, IDG says. Google Checkout, which is accepted at sites owned by Starbucks ( SBUX), Timberland ( TBL) and Jockey, lets people store their credit card information with Google so that they don't have to continually provide it to online merchants while they shop. The problems with the payment processing feature underscore the weakness with Google's product development outside of search. Google often brags about how it releases products "early" and fixes them later after receiving feedback from users. The company has argued that this approach to product development keeps it nimble.