Grid applications comprise several components and web-services that make them highly prone to the occurrence of transient software failures and aging problems. This type of failures often incur in undesired performance levels and unexpected partial crashes. In this paper we present a technique that offers high-availability for Grid services based on concepts like virtualization, clustering and software rejuvenation. To show the effectiveness of our approach, we have conducted some experiments with OGSA-DAI middleware. One of the implementations of OGSA-DAI makes use of Apache Axis V1.2.1, a SOAP implementation that suffers from severe memory leaks. Without changing any bit of the middleware layer we have been able to anticipate most of the problems caused by those leaks and to increase the overall availability of the OGSA-DAI Application Server. Although these results are tightly related with this middleware it should be noted that our technique is neutral and can be applied to any other Grid service that is supposed to be high-available.